pip install <安裝包> -i <鏡像源>

pip install beautifulsoup4 -i https://mirrors.aliyun.com/pypi/simple

Collecting beautifulsoup4
The repository located at mirrors.aliyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS it is recommended to use HTTPS instead, otherwise you may silence this warning and allow it anyways with ‘–trusted-host mirrors.aliyun.com'.
Could not find a version that satisfies the requirement beautifulsoup4 (from versions: )
No matching distribution found for beautifulsoup4

pip install beautifulsoup4 -i https://mirrors.aliyun.com/pypi/simple --trusted-host mirrors.aliyun.com  

pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple
pip config set trusted-host pypi.tuna.tsinghua.edu.cn

pip config set global.index-url  https://pypi.org/simple  
pip install xx -i https://pypi.org/simple

mkdir ~/.pip && touch ~/.pip/pip.conf

[global] 
index-url = https://pypi.tuna.tsinghua.edu.cn/simple/
[install] 
trusted-host = pypi.tuna.tsinghua.edu.cn

C:\Users\qxhgd\pip

[global] 
index-url = https://pypi.tuna.tsinghua.edu.cn/simple/
[install] 
trusted-host = pypi.tuna.tsinghua.edu.cn

pip config list

pip config -v list