1.找到fultter SDK所在文件夹的位置：依次进入 flutter/packages/flutter_tools/gradle 文件夹

1.1将buildscript repositories 下面的

  buildscript {
    repositories {
        google()
        mavenCentral()

    }
    ...
}

修改为

  buildscript {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }

    }
    ...
}

1.2 将DEFAULT_MAVEN_HOST 值修改成 "https://storage.flutter-io.cn"

private static final String DEFAULT_MAVEN_HOST = "https://storage.flutter-io.cn";

2 回到当前项目中，将android/build.gradle 文件中两处google() ，jcenter()替换掉,

buildscript {
   ...
    repositories {
//        google()
//        mavenCentral()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }

    }

   ...
}

allprojects {
    repositories {
//        google()
//        mavenCentral()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }

    }
}

3、clean后重新运行