This work investigates dynamics of a three-stage gear system in a new power-driven turret. This paper mainly consists to develop two kinds of dynamic models of the main drive train. One is the dynamic contact model of the gear system to calculate the dynamic meshing forces and the tooth root stresses. The other is a virtual prototype model adequately incorporating the deformability of the bearings to analyze the dynamical response. The dynamic meshing force and the tooth root stress were compared with the theoretically calculated results. The vibration acceleration signals of the turret were gathered by tests. According to the experimental data, the simulation results of the virtual prototype model were given based on which the rationality of the virtual prototype model is verified.