The problem is: the Firefox browser driver should be added to the Firefox browser installation directory, and the Firefox browser installation directory should be placed under the path. (I am careless, I forgot to put its corresponding driver under the Firefox browser)
Pro-test the following combinations are available:
pycharm-community-2017.3.4.exe
geckodriver-v0.20.0-win64
Python 3.6.5
selenium3.11.0
Firefox 56.0 (64 位)
Python 3.6.5
selenium3.11.0
Firefox 56.0 (64 位)
Note: Using the pycharm tool, if the above installation file is updated, the running code still reports an error, don't worry, restart pycharm, it should be fine.