A 3D rotary burrs grinding simulation system is described. By analyzing the structure of rotary burrs 4-axis NC grinding machine tool, rotary burrs grinding motion model is established. The method of axis direction decomposition based on 3D modeling is provided, which includes decomposing rotational part into simple primitive cells by using Visual C++ and OpenGL as the developing tools, and implementing the boolean operation between the part model and a tool sweeping solid dependent on the tool shape and tool trajectory for each tool movement. To use grinding machining simulation analysis of the interference resulted in grinding, main factors range is determined. Security region is identified in order to avoid interference between grinding wheel and the tooth surface, which can be used for guiding production of rotary burrs and improving the quality of grinding.