This paper established a high-speed tracked vehicle dynamics model, and simulated the transient response of sprocket when the vehicle is running at 60km/h on the D class road. the finite element model of the single tooth in mesh is established in Ansys and the rigid-flexible coupling model of "trackboard- sprocket" is established in RecurDyn. The dynamic stress and strain fringe of the sprocket’s gear ring is achieved by analysis. Simulation results show that the stress of tracked vehicle sprocket gear root and the fixed gear bolt hole is larger, and the stress concentration is detected at the edge of contacted tooth. The simulation results provide the calculation basis for the optimization of the high-speed tracked vehicle system and its lifespan prediction.