RV reducer is the core part of industrial robot. It is of great significance to study the dynamic characteristics because RV reducer produced in our country has a short life and high noise. Modal characteristics are the basis and the first step of studying dynamic characteristics. This paper establishes the finite element model of the main parts and completes modal simulation. The deviation between simulation and experiment is less than 5%, which means the accuracy of the finite element model and simulation results .Simplify bearing as bush element to connect the whole structure.The first three order natural frequenciesare far greater than the meshing frequency.There is no possibility of resonancein the external incentive. The whole works provide a reference for the further research of the dynamic characteristics of structure.