diff --git a/packages/core/src/services/image/adapters/openai.ts b/packages/core/src/services/image/adapters/openai.ts
index a292a22c..371f14a0 100644
--- a/packages/core/src/services/image/adapters/openai.ts
+++ b/packages/core/src/services/image/adapters/openai.ts
@@ -10,6 +10,19 @@ import type {
 import { ImageError } from '../errors'
 import { IMAGE_ERROR_CODES } from '../../../constants/error-codes'
 
+const GPT_IMAGE_2_SIZE_VALUES = [
+  '1024x1024',
+  '1536x1024',
+  '1024x1536',
+  '2048x2048',
+  '2048x1152',
+  '3840x2160',
+  '2160x3840',
+  'auto'
+] as const
+
+const GPT_IMAGE_2_BACKGROUND_VALUES = ['auto', 'opaque'] as const
+
 export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
   private static readonly FORCED_SINGLE_OUTPUT_PARAM_KEYS = ['n', 'batch_size', 'outputMimeType', 'response_format']
 
@@ -56,7 +69,7 @@ export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
             descriptionKey: 'image.params.size.description',
             type: 'string',
             defaultValue: '1024x1024',
-            allowedValues: ['1024x1024', '1536x1024', '1024x1536', 'auto']
+            allowedValues: [...GPT_IMAGE_2_SIZE_VALUES]
           },
           {
             name: 'quality',
@@ -72,7 +85,7 @@ export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
             descriptionKey: 'image.params.background.description',
             type: 'string',
             defaultValue: 'auto',
-            allowedValues: ['auto', 'transparent', 'opaque']
+            allowedValues: [...GPT_IMAGE_2_BACKGROUND_VALUES]
           }
         ],
         defaultParameterValues: {
@@ -145,7 +158,7 @@ export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
   }
 
   protected getParameterDefinitions(_modelId: string): readonly ImageParameterDefinition[] {
-    // GPT Image 1 使用统一的参数定义，n参数固定为1不暴露给用户
+    // GPT Image 2 使用统一的参数定义，n参数固定为1不暴露给用户
     return [
       {
         name: 'size',
@@ -153,7 +166,7 @@ export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
         descriptionKey: 'image.params.size.description',
         type: 'string',
         defaultValue: '1024x1024',
-        allowedValues: ['1024x1024', '1536x1024', '1024x1536', 'auto']
+        allowedValues: [...GPT_IMAGE_2_SIZE_VALUES]
       },
       {
         name: 'quality',
@@ -169,7 +182,7 @@ export class OpenAIImageAdapter extends AbstractImageProviderAdapter {
         descriptionKey: 'image.params.background.description',
         type: 'string',
         defaultValue: 'auto',
-        allowedValues: ['auto', 'transparent', 'opaque']
+        allowedValues: [...GPT_IMAGE_2_BACKGROUND_VALUES]
       }
     ]
   }
diff --git a/packages/core/tests/unit/image/openai-adapter.test.ts b/packages/core/tests/unit/image/openai-adapter.test.ts
index e58d3dfb..03f34447 100644
--- a/packages/core/tests/unit/image/openai-adapter.test.ts
+++ b/packages/core/tests/unit/image/openai-adapter.test.ts
@@ -54,20 +54,32 @@ describe('OpenAIImageAdapter', () => {
       })
     })
 
-    test('should include quality and size parameters', () => {
+    test('should expose supported GPT Image 2 parameters', () => {
       const models = adapter.getModels()
       const model = models.find(m => m.id === 'gpt-image-2')
 
       expect(model?.parameterDefinitions).toBeDefined()
       const qualityParam = model?.parameterDefinitions?.find(p => p.name === 'quality')
       const sizeParam = model?.parameterDefinitions?.find(p => p.name === 'size')
+      const backgroundParam = model?.parameterDefinitions?.find(p => p.name === 'background')
 
       expect(qualityParam).toBeDefined()
       expect(qualityParam?.type).toBe('string')
       expect(qualityParam?.allowedValues).toEqual(expect.arrayContaining(['auto', 'high', 'medium', 'low']))
 
       expect(sizeParam).toBeDefined()
-      expect(sizeParam?.allowedValues).toContain('1024x1024')
+      expect(sizeParam?.allowedValues).toEqual([
+        '1024x1024',
+        '1536x1024',
+        '1024x1536',
+        '2048x2048',
+        '2048x1152',
+        '3840x2160',
+        '2160x3840',
+        'auto'
+      ])
+
+      expect(backgroundParam?.allowedValues).toEqual(['auto', 'opaque'])
     })
   })
 
@@ -136,7 +148,7 @@ describe('OpenAIImageAdapter', () => {
         },
         paramOverrides: {
           quality: 'standard',
-          size: '1024x1024'
+          size: '3840x2160'
         }
       }
 
@@ -173,6 +185,7 @@ describe('OpenAIImageAdapter', () => {
 
       const [, options] = (global.fetch as any).mock.calls[0]
       const body = JSON.parse(options.body)
+      expect(body.size).toBe('3840x2160')
       expect(body.response_format).toBeUndefined()
     })