According to the online practice, Ubuntu reported another error after installing libgdiplus:

System.DllNotFoundException: Unable to load shared library ‘libSkiaSharp’ or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_ DEBUG environment variable: liblibSkiaSharp: cannot open shared object file: No such file or directory

Finally, I found a simpler solution for libgdiplus: nuget install the skiashrp.nativeassets.linux.nodependencies package

https://stackoverflow.com/questions/53693042/dllnotfoundexception-using-skiasharp-1-68-on-linux

Word to PDF is found to be garbled. After searching, it is found that Linux lacks Chinese fonts. Execute the following command

sudo apt-get install fonts-wqy-zenhei

After installing the Chinese font, the problem is solved