In order to overcome the difficulty in accurate prediction of the dynamic wear of tooth profile of precision RV reducer for industrial robot, this paper took BX-40E reducer as an example, obtained the wear coefficients under different position conditions through equivalent experiment based on the generalized Archard wear formula, with the consideration of the influence of different position conditions after the wear evolution in the wear prediction process. According to the deformation coordination theory and Langkali-Nikraves contact force model, the load distribution and contact pressure between teeth were determined. Considering the time-varying tooth profile wear and meshing force excitation, the numerical calculation model of dynamic tooth profile wear of transmission system was established by analytical modeling method. As compared with the tooth profile wear curve with the constant wear coefficient, both the wear value and the tooth surface distribution are significantly different, and the overall difference increases with the increase of wear times. The accuracy and necessity of quantifying the tooth surface wear with the wear coefficient taking into account the difference of contact position conditions were obtained. The wear depth curve of cycloid gear and needle teeth presents an asymmetric and irregular inverted “W” shape along the tooth profile. Due to the wear, the teeth near the tooth root and tooth top first fall off and then mesh, resulting in impact and micro protrusion peak. There is almost no wear at the concave convex transition position of cycloid tooth profile. With the increase of wear times, the wear peak area becomes narrower, and the non-uniform increase of wear rate slows down. There is a functional mapping relationship between the meshing force and the pressure angle. The results of the study provide a theoretical basis for improving the wear reduction and vibration reduction of cycloidal needle gear.