Hi Sougou
Please check that you have PyQt5 installed in Pycharm. Go to "File, Settings" in the mainmenu. Select "Project, Python Interpreter" in the settings window. Under the list of packages you should see "PyQt5", " PyQt5-Qt5" and "PyQt5-sip". Also make sure your python interpreter/virtual environment is correct.
I presume because it's looking for a dll that you are running something like Anaconda. Don't mix the install methods. Use either Conda install or pip install for all your packages in that environment.
Regards
Alan