To adapt to the complex layout structure of the chassis of hydrogen fuel cell vehicles and to save vehicle material costs, a lightweight optimization design method for the lower control arms of suspension components was constructed. This method integrates finite element modeling technology, response surface methodology, penalty function method, firefly algorithm as one. The static and dynamic characteristics of the lower control arm were analyzed, and the validity of the finite element model and analysis results were verified through modal testing. The structure mass of the lower control arm is selected as the optimization objective, with maximum deformation, maximum stress, and natural frequency as constraints. Through response surface method, the corresponding optimization model is established. Penalty function method is introduced to transform the constraints, and firefly optimization algorithm is employed for optimization, achieving lightweight optimization design of the lower control arm. The optimization results show that the structure mass of the lower control arm after optimization has been reduced by approximately 17.37%, with the maximum stress controlled at 67.32 MPa, a decrease of 9.93% compared to before optimization. This study achieves lightweight optimization of the lower control arm of hydrogen fuel cell vehicles, providing a reference method for the optimization of components and overall performance improvement of hydrogen fuel cell vehicles.