Abstract: Based on the Visual C++ 6.0, the design of tooth profile of the cycloidal gear is optimally programmed to improve its engaging condition, thus calculating the multi-mesh and tooth face contact conditions between the cycloid gear and ring-plate. A judgement is preliminarily made that the basic dimensions of reducer are reasonable. The design efficiency is improved to realize the calculation available to simulating analysis, which the traditional mechanical design cannot do. Taking advantages of the plentiful graphic API interface for the OpenGL, a kinematic simulation is carried out for the drive, by which the gear engagement in the planetary drive system can be displayed directly for observation.