1. The source of pip is wrong
[global]
timeout = 60
index-url = http://pypi.douban.com/simple
trusted-host = pypi.douban.com
2. The dependencies are not installed
sudo apt-get install libjpeg-dev zlib1g-dev
pip3 install Pillow
[global]
timeout = 60
index-url = http://pypi.douban.com/simple
trusted-host = pypi.douban.com
sudo apt-get install libjpeg-dev zlib1g-dev
pip3 install Pillow