Taking the RV reducer as the research object, the action form of parts machining and assembling errors on the transmission of the RV reducer are analyzed. Combining the translationtorsion coupling model of Lin with the error equivalence principle of mass spring, the mathematical model of dynamic transmission error of the system was established and solved. Based on the parameters of mathematical model, a threedimensional (3D) model with various errors was established and simulated by the dynamic simulation software of ADAMS. By testing and analyzing the input and output speed data of the RV reducer, the transmission error was 2″~40″ angle seconds, which was similar to the result of the mathematical model. Through the analysis of the frequency spectrums of transmission errors calculated by the mathematical model of the RV reducer and simulated by ADAMS, it was concluded that the main factor affecting the transmission error was the secondary cycloid pinwheel drive. The results of simulation verifies the accuracy of the mathematical model.