The following mirror stations are fast in China. Some are not in China, but they are very practical
//Mirrors.aliyun.com//AliCloud open source image (recommended in China)
//Mirrors.163.com//Netease 163 open-source mirror (recommended in China)
//Mirrors.sohu.com//Sohu open source mirror (domestic)
http://vault.centos.org //Centos official open source mirror (recommended abroad)
//Mirrors.ctyun.cn//Telecom Tianyi Cloud open source mirror station (domestic)
If the above common open source mirror stations cannot meet your needs, you can go to the official Centos recommendation to choose
//mirror-status.centos.org/#cn