diff --git a/README.md b/README.md
index 8f23d5dcd380..43d485fe2d74 100644
--- a/README.md
+++ b/README.md
@@ -314,7 +314,7 @@ docker run --name new-api -d --restart always \
 | `REDIS_CONN_STRING` | Redis connection string | - |
 | `STREAMING_TIMEOUT` | Streaming timeout (seconds) | `300` |
 | `STREAM_SCANNER_MAX_BUFFER_MB` | Max per-line buffer (MB) for the stream scanner; increase when upstream sends huge image/base64 payloads | `64` |
-| `MAX_REQUEST_BODY_MB` | Max request body size (MB, counted **after decompression**; prevents huge requests/zip bombs from exhausting memory). Exceeding it returns `413` | `32` |
+| `MAX_REQUEST_BODY_MB` | Max request body size (MB, counted **after decompression**; prevents huge requests/zip bombs from exhausting memory). Exceeding it returns `413` | `128` |
 | `AZURE_DEFAULT_API_VERSION` | Azure API version | `2025-04-01-preview` |
 | `ERROR_LOG_ENABLED` | Error log switch | `false` |
 | `PYROSCOPE_URL` | Pyroscope server address | - |
diff --git a/common/gin.go b/common/gin.go
index 5cad6e5c9512..b65572244d34 100644
--- a/common/gin.go
+++ b/common/gin.go
@@ -57,10 +57,7 @@ func GetRequestBody(c *gin.Context) (io.Seeker, error) {
 		}
 	}
 
-	maxMB := constant.MaxRequestBodyMB
-	if maxMB <= 0 {
-		maxMB = 128 // 默认 128MB
-	}
+	maxMB := constant.EffectiveMaxRequestBodyMB()
 	maxBytes := int64(maxMB) << 20
 
 	contentLength := c.Request.ContentLength
diff --git a/common/init.go b/common/init.go
index 4ac7d2384f07..fc8cd2e35438 100644
--- a/common/init.go
+++ b/common/init.go
@@ -133,7 +133,7 @@ func initConstantEnv() {
 	constant.MaxFileDownloadMB = GetEnvOrDefault("MAX_FILE_DOWNLOAD_MB", 64)
 	constant.StreamScannerMaxBufferMB = GetEnvOrDefault("STREAM_SCANNER_MAX_BUFFER_MB", 64)
 	// MaxRequestBodyMB 请求体最大大小（解压后），用于防止超大请求/zip bomb导致内存暴涨
-	constant.MaxRequestBodyMB = GetEnvOrDefault("MAX_REQUEST_BODY_MB", 128)
+	constant.MaxRequestBodyMB = GetEnvOrDefault("MAX_REQUEST_BODY_MB", constant.DefaultMaxRequestBodyMB)
 	// ForceStreamOption 覆盖请求参数，强制返回usage信息
 	constant.ForceStreamOption = GetEnvOrDefaultBool("FORCE_STREAM_OPTION", true)
 	constant.CountToken = GetEnvOrDefaultBool("CountToken", true)
diff --git a/constant/env.go b/constant/env.go
index d5aff1b0b173..b919d6ee34fb 100644
--- a/constant/env.go
+++ b/constant/env.go
@@ -1,5 +1,14 @@
 package constant
 
+const DefaultMaxRequestBodyMB = 128
+
+func EffectiveMaxRequestBodyMB() int {
+	if MaxRequestBodyMB <= 0 {
+		return DefaultMaxRequestBodyMB
+	}
+	return MaxRequestBodyMB
+}
+
 var StreamingTimeout int
 var DifyDebug bool
 var MaxFileDownloadMB int
diff --git a/constant/env_test.go b/constant/env_test.go
new file mode 100644
index 000000000000..7dee0b00ecbd
--- /dev/null
+++ b/constant/env_test.go
@@ -0,0 +1,29 @@
+package constant
+
+import "testing"
+
+func TestEffectiveMaxRequestBodyMB(t *testing.T) {
+	original := MaxRequestBodyMB
+	t.Cleanup(func() {
+		MaxRequestBodyMB = original
+	})
+
+	tests := []struct {
+		name  string
+		value int
+		want  int
+	}{
+		{name: "positive value", value: 64, want: 64},
+		{name: "zero falls back to default", value: 0, want: DefaultMaxRequestBodyMB},
+		{name: "negative falls back to default", value: -1, want: DefaultMaxRequestBodyMB},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			MaxRequestBodyMB = tt.value
+			if got := EffectiveMaxRequestBodyMB(); got != tt.want {
+				t.Fatalf("EffectiveMaxRequestBodyMB() = %d, want %d", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/middleware/gzip.go b/middleware/gzip.go
index 5e5682532f7a..dad4a75a7769 100644
--- a/middleware/gzip.go
+++ b/middleware/gzip.go
@@ -28,10 +28,7 @@ func DecompressRequestMiddleware() gin.HandlerFunc {
 			c.Next()
 			return
 		}
-		maxMB := constant.MaxRequestBodyMB
-		if maxMB <= 0 {
-			maxMB = 32
-		}
+		maxMB := constant.EffectiveMaxRequestBodyMB()
 		maxBytes := int64(maxMB) << 20
 
 		origBody := c.Request.Body