As one of the important performance parameters of planetary gear transmission,transmission error reflects the precision problem at work,while the tooth surface wear caused by long-time work will affect the transmission precision.In view of this problem,taking 3z-Ⅱ type planetary gear as the research object,considering the inherent error of gear and installation error of each part,the whole transmission system transmission error model was established.By using probability analysis and Monte Carlo method for simulation calculation, theory transmission error model closed to the actual was obtained.Then,based on Archard wear model and Hertz contact model,the gear wear model was established.The wear depth of each gear was obtained,and the wear depth of each gear was equivalent to the tooth profile error,and the transmission error model based on the tooth surface wear was established.By comparing and analyzing the simulation results of the two models,the transmission error of the whole transmission system increases when considering wear,the transmission error is concentrated in -0.42′ to 3.75′,the average value is 1.71′;compared with no wear,the positive transmission error increases and the negative value decreases.