Abstract: In order to reveal the dynamic relationship between the tooth top modification amount and the meshing impact of the gear pair, the paper firstly established an analytical computational model for the meshing impact excitation of the gear pair after the tooth top modification,so as to clarify the evolution law between the modification amount and the maximum meshing impact force of the gear pair; then, an analytical formula for calculating the time-varying meshing stiffness of gear pairs with tooth top modification was provided, and the influence of tooth top modification on meshing stiffness was studied; furthermore, the dynamics model of the planetary wheel system was constructed to calculate the equalization coefficient of the planetary wheel system and to clarify the system load distribution capacity after tooth top modification. The results showed that, as the amount of tooth top modification increased, the meshing impact force of the gear pair decreased; the time-varying meshing stiffness curve of the gear pair showed a marked abrupt variation after tooth top modification; the tooth top modification reduced the fluctuation of the dynamic load sharing coefficient of the transmission system, and the dynamic load sharing coefficient change caused by meshing impact was stable after the modification, and the load sharing performance was improved.