diff --git a/packages/model-runtime/src/core/streams/qwen.test.ts b/packages/model-runtime/src/core/streams/qwen.test.ts
index 923282cf66..4da2aa735e 100644
--- a/packages/model-runtime/src/core/streams/qwen.test.ts
+++ b/packages/model-runtime/src/core/streams/qwen.test.ts
@@ -621,6 +621,326 @@ describe('QwenAIStream', () => {
   });
 });
 
+// Test case for parallel tool calls bug (LOBE-3903)
+// This test reproduces the issue where Qwen model returns 3 parallel tool calls
+// for querying time in Beijing, Shanghai, and Nanjing simultaneously.
+// The bug causes arguments from different tool calls to be incorrectly merged.
+describe('parallel tool calls streaming bug', () => {
+  it('should handle 3 parallel tool calls with incremental arguments (Qwen qwen3-max behavior)', async () => {
+    // This test simulates the exact stream pattern from the bug report:
+    // User asks: "查一下北京、上海、南京的时间，同时调用3次mcp"
+    // Model returns 3 parallel tool calls with index 0, 1, 2
+    // Subsequent chunks contain arguments without id field, only index
+    const streamId = 'chatcmpl-23f324a2-059f-9ab4-b7b3-f47bcba5ebf7';
+
+    // Define all chunks as an array for clarity and maintainability
+    const chunks = [
+      // Chunk 0: First tool call starts (index=0)
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              role: 'assistant',
+              tool_calls: [
+                {
+                  id: 'call_c7d8b4984a4d4f54a4956bca',
+                  type: 'function',
+                  function: { name: 'time____get_time____mcp', arguments: '' },
+                  index: 0,
+                },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 1: First tool call continues with empty arguments
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                {
+                  id: 'call_c7d8b4984a4d4f54a4956bca',
+                  type: 'function',
+                  function: { arguments: '' },
+                  index: 0,
+                },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 2: First tool call arguments part 1 (北京)
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                { type: 'function', function: { arguments: '{"location": "北京' }, index: 0 },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 3: First tool call arguments part 2
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: { tool_calls: [{ type: 'function', function: { arguments: '"}' }, index: 0 }] },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 4: Empty arguments for first tool call
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: { tool_calls: [{ type: 'function', function: { arguments: '' }, index: 0 }] },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 5: Second tool call starts (index=1) - 上海
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                {
+                  id: 'call_f564785a14534d9a8c5ee641',
+                  type: 'function',
+                  function: { name: 'time____get_time____mcp', arguments: '' },
+                  index: 1,
+                },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 6: Second tool call arguments (上海)
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                { type: 'function', function: { arguments: '{"location": "上海' }, index: 1 },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 7: Second tool call arguments part 2
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: { tool_calls: [{ type: 'function', function: { arguments: '"}' }, index: 1 }] },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 8: Third tool call starts (index=2) - 南京
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                {
+                  id: 'call_19693813aebd434aab821f06',
+                  type: 'function',
+                  function: { name: 'time____get_time____mcp', arguments: '{"location": "' },
+                  index: 2,
+                },
+              ],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 9: Third tool call arguments (南京)
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [{ type: 'function', function: { arguments: '南京"' }, index: 2 }],
+            },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 10: Third tool call arguments final
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [
+          {
+            index: 0,
+            delta: { tool_calls: [{ type: 'function', function: { arguments: '}' }, index: 2 }] },
+            finish_reason: null,
+          },
+        ],
+      },
+      // Chunk 11: Finish
+      {
+        id: streamId,
+        object: 'chat.completion.chunk',
+        created: 1768906556,
+        model: 'qwen3-max',
+        choices: [{ index: 0, delta: {}, finish_reason: 'tool_calls' }],
+      },
+    ];
+
+    const mockOpenAIStream = new ReadableStream({
+      start(controller) {
+        chunks.forEach((chunk) => controller.enqueue(chunk));
+        controller.close();
+      },
+    });
+
+    let aggregatedToolCalls: any[] = [];
+
+    const protocolStream = QwenAIStream(mockOpenAIStream, {
+      callbacks: {
+        onToolsCalling: ({ toolsCalling }) => {
+          aggregatedToolCalls = toolsCalling;
+        },
+      },
+    });
+
+    const decoder = new TextDecoder();
+    const outputChunks: string[] = [];
+
+    // @ts-ignore
+    for await (const chunk of protocolStream) {
+      outputChunks.push(decoder.decode(chunk, { stream: true }));
+    }
+
+    // Verify streaming chunks output format (SSE protocol)
+    // Each tool call chunk should have correct id based on its index
+    expect(outputChunks).toEqual([
+      // Chunk 0: First tool call starts (index=0)
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"","name":"time____get_time____mcp"},"id":"call_c7d8b4984a4d4f54a4956bca","index":0,"type":"function"}]\n\n',
+      // Chunk 1: First tool call continues
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"","name":null},"id":"call_c7d8b4984a4d4f54a4956bca","index":0,"type":"function"}]\n\n',
+      // Chunk 2: First tool call arguments part 1
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"{\\"location\\": \\"北京","name":null},"id":"call_c7d8b4984a4d4f54a4956bca","index":0,"type":"function"}]\n\n',
+      // Chunk 3: First tool call arguments part 2
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"\\"}","name":null},"id":"call_c7d8b4984a4d4f54a4956bca","index":0,"type":"function"}]\n\n',
+      // Chunk 4: Empty arguments
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"","name":null},"id":"call_c7d8b4984a4d4f54a4956bca","index":0,"type":"function"}]\n\n',
+      // Chunk 5: Second tool call starts (index=1) - should have its own id
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"","name":"time____get_time____mcp"},"id":"call_f564785a14534d9a8c5ee641","index":1,"type":"function"}]\n\n',
+      // Chunk 6: Second tool call arguments - should use index=1's stored id
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"{\\"location\\": \\"上海","name":null},"id":"call_f564785a14534d9a8c5ee641","index":1,"type":"function"}]\n\n',
+      // Chunk 7: Second tool call arguments part 2
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"\\"}","name":null},"id":"call_f564785a14534d9a8c5ee641","index":1,"type":"function"}]\n\n',
+      // Chunk 8: Third tool call starts (index=2)
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"{\\"location\\": \\"","name":"time____get_time____mcp"},"id":"call_19693813aebd434aab821f06","index":2,"type":"function"}]\n\n',
+      // Chunk 9: Third tool call arguments - should use index=2's stored id
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"南京\\"","name":null},"id":"call_19693813aebd434aab821f06","index":2,"type":"function"}]\n\n',
+      // Chunk 10: Third tool call arguments final
+      `id: ${streamId}\n`,
+      'event: tool_calls\n',
+      'data: [{"function":{"arguments":"}","name":null},"id":"call_19693813aebd434aab821f06","index":2,"type":"function"}]\n\n',
+      // Chunk 11: Finish
+      `id: ${streamId}\n`,
+      'event: stop\n',
+      'data: "tool_calls"\n\n',
+    ]);
+
+    // Verify aggregated tool calls have correct arguments (not merged incorrectly)
+    expect(aggregatedToolCalls).toHaveLength(3);
+    expect(aggregatedToolCalls[0]).toMatchObject({
+      id: 'call_c7d8b4984a4d4f54a4956bca',
+      function: { name: 'time____get_time____mcp', arguments: '{"location": "北京"}' },
+    });
+    expect(aggregatedToolCalls[1]).toMatchObject({
+      id: 'call_f564785a14534d9a8c5ee641',
+      function: { name: 'time____get_time____mcp', arguments: '{"location": "上海"}' },
+    });
+    expect(aggregatedToolCalls[2]).toMatchObject({
+      id: 'call_19693813aebd434aab821f06',
+      function: { name: 'time____get_time____mcp', arguments: '{"location": "南京"}' },
+    });
+  });
+});
+
 describe('transformQwenStream', () => {
   it('should handle usage chunk', () => {
     const mockChunk: OpenAI.ChatCompletionChunk = {
diff --git a/packages/model-runtime/src/core/streams/qwen.ts b/packages/model-runtime/src/core/streams/qwen.ts
index 733e5f4543..4e9d5c2ece 100644
--- a/packages/model-runtime/src/core/streams/qwen.ts
+++ b/packages/model-runtime/src/core/streams/qwen.ts
@@ -70,17 +70,26 @@ export const transformQwenStream = (
 
   if (item.delta?.tool_calls) {
     return {
-      data: item.delta.tool_calls.map((value, index): StreamToolCallChunkData => {
-        // Store first tool call's info in streamContext for subsequent chunks
-        // (similar pattern to OpenAI stream handling)
-        if (streamContext && !streamContext.tool && value.id && value.function?.name) {
-          streamContext.tool = {
+      data: item.delta.tool_calls.map((value, arrayIndex): StreamToolCallChunkData => {
+        // Get the actual tool index from the chunk, fallback to array position
+        const toolIndex = typeof value.index !== 'undefined' ? value.index : arrayIndex;
+
+        // Store tool call info in streamContext.tools map by index for parallel tool calls
+        // This allows us to correctly track multiple tools being called in parallel
+        if (streamContext && value.id && value.function?.name) {
+          if (!streamContext.tools) {
+            streamContext.tools = {};
+          }
+          streamContext.tools[toolIndex] = {
             id: value.id,
-            index: typeof value.index !== 'undefined' ? value.index : index,
+            index: toolIndex,
             name: value.function.name,
           };
         }
 
+        // Get stored tool info for this index (for incremental chunks without id)
+        const storedTool = streamContext?.tools?.[toolIndex];
+
         return {
           // Qwen models may send tool_calls in two separate chunks:
           // 1. First chunk: {id, name} without arguments
@@ -91,10 +100,10 @@ export const transformQwenStream = (
             arguments: value.function?.arguments ?? '',
             name: value.function?.name ?? null,
           },
-          // For incremental chunks without id, use the stored tool id from streamContext
-          id:
-            value.id || streamContext?.tool?.id || generateToolCallId(index, value.function?.name),
-          index: typeof value.index !== 'undefined' ? value.index : index,
+          // For incremental chunks without id, use the stored tool id from streamContext.tools
+          // based on the tool index to correctly associate arguments with the right tool call
+          id: value.id || storedTool?.id || generateToolCallId(toolIndex, value.function?.name),
+          index: toolIndex,
           type: value.type || 'function',
         };
       }),