As the energy source of the formula student electric car, the battery pack must meet the racing performance and driving range requirements of the car at the same time. Consequently, lightweight design of the battery box assumes paramount importance within the context of formula student electric racing car. In this paper, the material selection of the battery box is carried out according to the basic principle of entropy weight-TOPSIS method. 5052H32 was ultimately selected for the battery box. A dynamic-static characteristic model of the power battery box is constructed, followed by finite element analysis using ANSYS. The strength of the battery box structure is checked under five classic working conditions. The battery box undergoes strength verification and structure optimization, resulting in a 17.3% weight reduction, while maintaining the integrity of its structural strength. Under these five representative scenarios, the maximum stress is 81.906 MPa in 40 g backward acceleration conditions, significantly lower than the yield strength of the selected material. The final battery box design meets the rules of Formula Student Electric China and meets the team’s development goals for the season.