Based on Ansys parametric model, the relationship between design variables and optimization objectives was studied, and the effective combination of different sheet thickness was explored, which could obtain the global optimal solution to realize body light weight quantization. Aiming at the light weight case of tramcar body, the flow of vehicle body light weight scheme was proposed, which determined the optimization variables through DOE calculation and sensitivity analysis, and explored the design space of optimization variables, providing a reference basis for vehicle body improvement. The optimization results showed that the light weight design of the vehicle body could achieve significant weight loss and the whole optimization process could be reused.