In order to optimize the vibration fatigue characteristics of the equipment cabin bottom plate, a rigid-flexible coupled multi-body dynamic model is established, and the relationship between the vibration of the key position of the floor and the vehicle speed is analyzed under the Wuguang spectrum. It is found that the overall vibration of vehicle equipment cabin bottom plate is increasing with the speed, but at 250km/h, the longitudinal acceleration amplitude is larger than 300km/h. Then according to the dynamic simulation results, the loads is extracted and the finite element strength analysis is performed. The maximum stress of the whole bottom plate and the maximum stress around the hole are obtained. The rolling table test data is consistent with the simulation results. Finally, the bottom plate is optimized to thicken the plate thickness. By comparison, the overall maximum stress after optimization is reduced from 8.78 MPa to 4.79 MPa, and the maximum stress around the hole is reduced from 1.65 MPa to 0.95 MPa. The strength performance of the bottom plate has been greatly improved.