diff --git a/src/main/services/VolcengineService.ts b/src/main/services/VolcengineService.ts
index 47f5b80394..ae75d07f9a 100644
--- a/src/main/services/VolcengineService.ts
+++ b/src/main/services/VolcengineService.ts
@@ -69,11 +69,15 @@ export function _buildCanonicalHeaders(headers: Record<string, string>): {
   canonicalHeaders: string
   signedHeaders: string
 } {
-  const sortedKeys = Object.keys(headers)
-    .map((k) => k.toLowerCase())
-    .sort()
+  // Create a lowercase-keyed map to handle mixed-case input headers
+  const lowercaseHeaders: Record<string, string> = {}
+  for (const [key, value] of Object.entries(headers)) {
+    lowercaseHeaders[key.toLowerCase()] = value
+  }
 
-  const canonicalHeaders = sortedKeys.map((key) => `${key}:${headers[key]?.trim() || ''}`).join('\n') + '\n'
+  const sortedKeys = Object.keys(lowercaseHeaders).sort()
+
+  const canonicalHeaders = sortedKeys.map((key) => `${key}:${lowercaseHeaders[key]?.trim() || ''}`).join('\n') + '\n'
 
   const signedHeaders = sortedKeys.join(';')
 
diff --git a/src/main/services/__tests__/VolcengineService.test.ts b/src/main/services/__tests__/VolcengineService.test.ts
index 789bd93116..955adc0331 100644
--- a/src/main/services/__tests__/VolcengineService.test.ts
+++ b/src/main/services/__tests__/VolcengineService.test.ts
@@ -292,6 +292,21 @@ describe('VolcengineService', () => {
 
         expect(result.canonicalHeaders).toBe('host:example.com\nx-custom:\n')
       })
+
+      it('should handle mixed-case header keys', () => {
+        const headers = {
+          'X-Date': '20240101T120000Z',
+          'Content-Type': 'application/json',
+          Host: 'example.com'
+        }
+
+        const result = _buildCanonicalHeaders(headers)
+
+        expect(result.canonicalHeaders).toBe(
+          'content-type:application/json\nhost:example.com\nx-date:20240101T120000Z\n'
+        )
+        expect(result.signedHeaders).toBe('content-type;host;x-date')
+      })
     })
 
     describe('deriveSigningKey', () => {