Abstract: This topic is about the design of planetary gear reducer, the internal deceleration device of deceleration clutch of automatic washing machine. The use of planetary gear train reducer in washing machine is the use of planetary gear transmission: small size, light weight, compact structure and large bearing capacity; High transmission efficiency; The transmission is relatively large; Smooth movement, strong impact and vibration resistance and low noise. In fact, planetary gear reduction is the principle of gear reduction. It has a gear with a fixed axis called the central wheel or sun gear, and a gear with a variable axis on the edge of sun gear, that is, the gear that rotates and revolves is called the planetary gear, and the planetary gear has a supporting part called the planetary carrier, which transmits the power to the shaft and then to other gears. They consist of a group of several gears. There is only one prime Mover, and this epicyclic gear train is called a planetary gear train. The first chapter of the catalogue is an overview, and the third chapter is a brief introduction to the reducer. ........................................................................................................................................ ............................... coefficient and contact fatigue limit ................................. 15 Chapter VI Design of gear transmission between planetary carrier and output shaft .............. 17 (1) Selection of gear material and accuracy grade Calculation of bending fatigue strength of ................ root ........... 19 (1) Design of input shaft of reducer ......................................... 19 1. Determine the allowable stress and determine the length of each shaft section.