diff --git a/backend/app/services/cover_generation_service.py b/backend/app/services/cover_generation_service.py
index e9d3752..399e8f2 100644
--- a/backend/app/services/cover_generation_service.py
+++ b/backend/app/services/cover_generation_service.py
@@ -3,10 +3,12 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 from datetime import datetime
+import json
 from pathlib import Path
 from typing import Optional
 from urllib.parse import quote
 
+import httpx
 from fastapi import HTTPException
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -99,12 +101,25 @@ class CoverGenerationService:
                 "model": result["model"],
                 "message": "封面生成成功",
             }
+        except httpx.HTTPStatusError as exc:
+            logger.error("封面生成上游 HTTP 错误: project_id=%s error=%s", project.id, exc, exc_info=True)
+            detail = self._extract_upstream_error_detail(exc)
+            project.cover_status = "failed"
+            project.cover_error = detail
+            await db.commit()
+            raise HTTPException(status_code=exc.response.status_code, detail=detail) from exc
+        except HTTPException as exc:
+            logger.error("封面生成业务错误: project_id=%s error=%s", project.id, exc.detail, exc_info=True)
+            project.cover_status = "failed"
+            project.cover_error = str(exc.detail)
+            await db.commit()
+            raise
         except Exception as exc:
             logger.error("封面生成失败: project_id=%s error=%s", project.id, exc, exc_info=True)
             project.cover_status = "failed"
             project.cover_error = str(exc)
             await db.commit()
-            raise HTTPException(status_code=500, detail=f"封面生成失败: {exc}") from exc
+            raise HTTPException(status_code=500, detail=str(exc)) from exc
 
     async def test_cover_settings(
         self,
@@ -126,12 +141,17 @@ class CoverGenerationService:
             "Create a clean fantasy novel cover illustration, vertical book cover, "
             "standard 2:3 ratio, atmospheric lighting, no text, no watermark."
         )
-        await provider_instance.generate_cover(
-            prompt=test_prompt,
-            model=model,
-            width=COVER_WIDTH,
-            height=COVER_HEIGHT,
-        )
+        try:
+            await provider_instance.generate_cover(
+                prompt=test_prompt,
+                model=model,
+                width=COVER_WIDTH,
+                height=COVER_HEIGHT,
+            )
+        except httpx.HTTPStatusError as exc:
+            detail = self._extract_upstream_error_detail(exc)
+            raise HTTPException(status_code=exc.response.status_code, detail=detail) from exc
+
         return CoverTestResult(
             success=True,
             message="封面图片接口测试成功",
@@ -243,5 +263,37 @@ class CoverGenerationService:
 
         raise HTTPException(status_code=404, detail="封面文件路径无效，请重新生成")
 
+    @staticmethod
+    def _extract_upstream_error_detail(exc: httpx.HTTPStatusError) -> str:
+        response = exc.response
+        if response is None:
+            return str(exc)
+
+        try:
+            data = response.json()
+        except json.JSONDecodeError:
+            text = response.text.strip()
+            return text or str(exc)
+
+        if isinstance(data, dict):
+            for key in ("detail", "message", "error", "msg"):
+                value = data.get(key)
+                if isinstance(value, str) and value.strip():
+                    return value.strip()
+                if isinstance(value, dict):
+                    for nested_key in ("message", "detail", "msg"):
+                        nested_value = value.get(nested_key)
+                        if isinstance(nested_value, str) and nested_value.strip():
+                            return nested_value.strip()
+                if isinstance(value, list) and value:
+                    first_item = value[0]
+                    if isinstance(first_item, str) and first_item.strip():
+                        return first_item.strip()
+
+        text = response.text.strip()
+        if text:
+            return text
+        return str(exc)
+
 
 cover_generation_service = CoverGenerationService()
diff --git a/backend/app/services/cover_providers/gemini_cover_provider.py b/backend/app/services/cover_providers/gemini_cover_provider.py
index ef6de3e..a9719c6 100644
--- a/backend/app/services/cover_providers/gemini_cover_provider.py
+++ b/backend/app/services/cover_providers/gemini_cover_provider.py
@@ -27,7 +27,7 @@ class GeminiCoverProvider(BaseCoverProvider):
         width: int,
         height: int,
     ) -> CoverGenerationResult:
-        url = f"{self.base_url}/models/{model}:generateContent?key={self.api_key}"
+        url = f"{self.base_url}/models/{model}:generateContent"
         payload: dict[str, Any] = {
             "contents": [{
                 "role": "user",
@@ -43,11 +43,27 @@ class GeminiCoverProvider(BaseCoverProvider):
                 "temperature": 0.4,
             },
         }
+        headers = {
+            "x-goog-api-key": self.api_key,
+            "Content-Type": "application/json",
+        }
+
+        try:
+            async with httpx.AsyncClient(timeout=120.0) as client:
+                response = await client.post(url, headers=headers, json=payload)
 
-        async with httpx.AsyncClient(timeout=120.0) as client:
-            response = await client.post(url, json=payload)
             response.raise_for_status()
             data = response.json()
+        except httpx.HTTPStatusError as exc:
+            logger.error(
+                "Gemini 封面生成 HTTP 错误: status=%s response=%s",
+                exc.response.status_code if exc.response else None,
+                exc.response.text[:2000] if exc.response is not None else None,
+            )
+            raise
+        except Exception:
+            logger.error("Gemini 封面生成请求异常", exc_info=True)
+            raise
 
         candidates = data.get("candidates") or []
         if not candidates: