For improving the working environment and polishing quality, the robotic polishing has received more and more attention, which puts forward higher requirement for the motion path planning. Correct understanding and flexible using of coordinate system can bring great convenience to the programming and debugging. Based on a practical engineering project, the robotic coordinate system was described and the polishing process of robot was analyzed specifically, and the application of each coordinate system in different grinding phases was explained in detailed , which implemented the efficiency of trajectory programming and compensation of tool wear.