import os

path = 'E:\\_pkgs_'
cmd = 'pip download -d ' + path + ' ' + 'pkg_name' + ' ' + '-i  https://pypi.tuna.tsinghua.edu.cn/simple/'
print(cmd)

with open('requirements.txt', 'r') as f:
    for line in f.readlines():
        result = os.system(cmd.replace('pkg_name', line.strip()))

然后切换到path目录下，执行

pip install --no-index --find-links=E:\\_pkgs_ -r requirements.txt

requirements.txt是包列表。