Abstract: Aiming at the structural strength redundancy of the frame of an electric moped (hereinafter referred to as electric moped), a lightweight method for the electric moped frame based on geometric optimization analysis is proposed. Based on the finite element model of the electric moped frame, this paper establishes its optimization model and determines the optimal design variables of the frame through geometric optimization analysis. Then, the optimal section size is obtained via the thickness dimension optimization strategy. The maximum static Von Mises stress of the optimized frame is within the constrained allowable stress range. The weight of the electric moped body is reduced by 23% after optimization, achieving the minimum body weight. The lightweight scheme not only contributes to the "dual carbon" goals, but also meets the performance requirements of the electric moped in terms of speed, power and cruising range.