In order to obtain a face gear transmission mechanism with the high meshing stability, the method of 3D topological modification method with computer aided design technology was proposed in the spiroid face gear. The gear meshing pair with point contact surface can be gotten by calculated,it avoided the edge contact phenomenon. Firstly, the modification model of contact path was established by presetting a transmission error function along the desired contact path, the spiroid face gear was generated by the principle of slotting. Then the modification model of contact line was constructed by Computer aided design technology, it was carried out on the same spiroid face gear. The tooth surface based on the 3D topological modification was reconstructed through the superposition of the two modifications amount, it achieved point contact in the double convex face gear transmission. Finally, tooth contact analysis (TCA) of the spiroid face gear with two different design parameters was accomplished. The result shows that the design parameters are highly consistent with the simulation results, and the rationality of the topological modification method with computer aided design technology is verified. [ABSTRACT FROM AUTHOR]