The automotive industry has experienced rapid development in recent years, with a significant increase in the number of vehicles in China. To effectively reduce the energy consumption and carbon emissions of automobiles, implementing lightweight design for the steering knuckle structure is essential. In this paper, in order to prepare steering knuckle parts with less weight, the material of steering knuckle was changed from 40Cr to polyether ether ketone (PEEK), which has less density, while maintaining the performance of the part. Fused deposition molding (FDM) technology, as one of the main methods of thermoplastic material manufacturing, has the ability to machine any complex geometrical structure, which greatly enhances the degree of design freedom. However, in the case of FDM technology, the print parameters determine the performance of the printed sample. Based on this, this paper will explore the influence of process parameters on the mechanical properties of PEEK materials through orthogonal experiments to screen out the optimal parameter combinations for printing. For the printing layer height of 0.1mm, the temperature of the holding chamber is 90 ℃, the filling method for the spiral tetrahedron. The PEEK materials molded under the optimal parameters of FDM were insulated to investigate the effect of the heat treatment process on the mechanical properties of PEEK materials. The loaded condition of the steering knuckle in each working condition is calculated by the basic parameters of the car, the dangerous cross section of the part is determined by simulation, and the structural optimal design of the part is carried out by topology optimization. Under the premise of ensuring its mechanical properties, minimize the amount of material to achieve the goal of lightweight.