一般的，系统图标存在/usr/share/applications/

以制作PyChrom图标为例

sudo gedit /usr/share/applications/Pycharm.desktop

[Desktop Entry]
Type=Application
Name=Pycharm
GenericName=Pycharm3
Comment=Pycharm3:The Python IDE
Exec="/XXX/pycharm-community-3.4.1/bin/pycharm.sh" %f
Icon=/XXX/pycharm-community-3.4.1/bin/pycharm.png
Terminal=pycharm
Categories=Pycharm;