diff --git a/backend/internal/app/provider_image.go b/backend/internal/app/provider_image.go
index 7d10ad9b7..3bc21e4e2 100644
--- a/backend/internal/app/provider_image.go
+++ b/backend/internal/app/provider_image.go
@@ -303,7 +303,7 @@ func grokImageRequestBody(input canvasGenerationInput) (grokImageRequest, string
 		Model:          input.Config.Model,
 		Prompt:         withSystemPrompt(input.Config, input.Prompt),
 		N:              1,
-		ResponseFormat: "url",
+		ResponseFormat: grokImageResponseFormat(input.ImageCapability),
 		// Grok 图片协议用 aspect_ratio 表达画布比例；同时发送 size 会被上游按 OpenAI 枚举校验并拒绝。
 		AspectRatio: normalizeGrokImageAspectRatio(input.Config.Size),
 		Resolution:  normalizeGrokImageResolution(input.Config.Quality),
@@ -322,6 +322,13 @@ func grokImageRequestBody(input canvasGenerationInput) (grokImageRequest, string
 	return body, "/images/edits", nil
 }
 
+func grokImageResponseFormat(profile *ImageCapabilityConfig) string {
+	if imageParameterSupported(profile, "response_format") {
+		return "b64_json"
+	}
+	return "url"
+}
+
 // normalizeGrokImageResolution 把画布 quality（1k/2k/high…）映射为 grok2api / xAI 的 resolution。
 func normalizeGrokImageResolution(quality string) string {
 	raw := strings.ToLower(strings.TrimSpace(quality))
diff --git a/backend/internal/app/provider_protocol_request.go b/backend/internal/app/provider_protocol_request.go
index 9307b2de4..028538dab 100644
--- a/backend/internal/app/provider_protocol_request.go
+++ b/backend/internal/app/provider_protocol_request.go
@@ -91,6 +91,14 @@ func protocolRequestFromInput(input canvasGenerationInput) protocol.GenerationRe
 			}
 		}
 	}
+	if input.Mode == "image" && input.Config.InterfaceType == string(model.ChannelInterfaceGrokImage) {
+		options := make(map[string]any)
+		for name, value := range request.ProviderOptions[input.Config.InterfaceType] {
+			options[name] = value
+		}
+		options["response_format"] = grokImageResponseFormat(input.ImageCapability)
+		request.ProviderOptions[input.Config.InterfaceType] = options
+	}
 	return request
 }
 
diff --git a/backend/internal/protocol/docs/grok-image.md b/backend/internal/protocol/docs/grok-image.md
index 143a13898..7263ea55e 100644
--- a/backend/internal/protocol/docs/grok-image.md
+++ b/backend/internal/protocol/docs/grok-image.md
@@ -50,6 +50,8 @@ curl "{channel_base_url}/v1/images/generations" \
 
 ## 响应与错误
 
+模型能力配置中的 `response_format` 开关控制请求的返回格式：开启发送 `b64_json`，关闭发送 `url`。声明式插件和后端 Grok 手写路径共用此映射。xAI 零数据保留团队应开启该选项；Base64 图片由已有响应解析器接收，不需要另设接收开关。
+
 插件按 OpenAI Images 风格解析 `data[]` 中的 `url`、`b64_json` 或 `data`。如果 xAI 的实际响应结构发生变化或只返回异步任务，当前解析会失败而不是伪造结果。素材不可达、比例/分辨率不受模型支持、模型无权限和审核拒绝应原样暴露。
 
 ## 官方资料