CVD diamond is the main trend of future diamond materials. Surface uniformity of CVD diamond film polishing is one of the key technologies to expand the application of CVD diamond. Based on the catalytic polishing method, rotation velocity of the planet wheel is achieved when the lapping plate is in different rotation velocity and different bias distance by mechanics analysis. The lapping surface uniformity is analyzed to find out the best bias distance and velocity ratio by simulating the lapping times of different CVD diamond film with different velocity ratio and bias distance. At last, the lapping planet velocity and bias distance are achieved when polishing is in the best condition. The high uniformity surface can be achieved when polishing is carried out in these parameters.