After the precise gear change model of spur gear is established in the software of SolidWorks. Through the comparison and analysis of whether there is a common divisor between the meshed pairs of gears, whether the number of teeth of the sun gear is an integral multiple of the number of planetary gears, and different tooth number schemes under different input ends of the planetary gear train, the following conclusions are obtained:
(1) When there is a reciprocal relationship between the number of teeth of the meshing gear pair, the tooth surface stress basically does not have the phenomenon of eccentric load, and it is most important to meet the mutual quality between the planetary gear and the inner ring gear;
(2) When the number of sun gear teeth is not an integral multiple of the number of planetary gears, the transmission error, meshing stiffness and tooth surface contact stress of planetary gear train are better than those that can be divided;
(3) When the planetary carrier is used as the input end of the involute planetary gear reducer, its working performance is better than that when the sun gear and inner ring gear are used as the input end.