In order to adapt to the development of urban electric buses and the needs of national energy conservation and environmental protection policies，a lightweight method for vehicle body structure is proposed in this paper based on sensitivity analysis of the static strength and rollover safety performance of electric buses. Firstly，a finite element model of a certain electric bus is established，and the static strength and rollover safety analysis of the body structure is conducted through the finite element method. Secondly，sensitivity analysis of the static strength and rollover safety of the vehicle body under bending and twisting conditions is conducted on the finite element model. Based on the sensitivity analysis results，the component plate thickness that is beneficial for lightweighting and has little impact on the static strength and rollover safety of the vehicle body is selected as the design variable. The size optimization is carried out with the goal of minimizing the mass of the vehicle body skeleton，and the constraint that the maximum von Mises stress of each material unit does not exceed its material yield strength. The optimization results indicate that the static strength and rollover safety performance of the vehicle body structure meet regulatory requirements，and the weight of the vehicle body frame is reduced by 3.8%.