The cycloid gear is the key component of the RV reducer, and the hole structure of the cycloid gear has a great influence on the transmission stability of the of the RV reducer. Based on the meshing contact analysis between the cycloid gear and pin of transmission system, the number of actual meshing teeth pairs of the cycloid gear were obtained. The meshing angle of each tooth pair and the comprehensive meshing stiffness were calculated. Taking the comprehensive meshing stiffness as elastic constraint condition in finite element software, the dynamics harmonic resonance analysis of cycloid gear was carried out. The position of maximum vibration and deformation is located at the fan-shaped lightening hole of cycloid gear plate. According to the different shape of fan-shaped holes of cycloid gear, the dynamics simulation was carried out by orthogonal test with three factors and four levels. The results show that the radius of the top and bottom circle of the fan-shaped hole is always the key factor to the vibration of the cycloidal wheel with the increase of rotation speed, while the vibration increases gradually for the radius of the inverted circle, and decreases for the angle between the waist and the waist. The conclusions are helpful for the structure design of cycloid gear wheel.