Using polylactic acid (PLA) as the material for fused deposition modeling (FDM) 3D printing, the study optimized tensile strength as the performance indicator. By conducting single-factor tests and employing response surface methodology (RSM), the effects of four main process parameters (printing layer thickness, printing orientation, infilling density, and printing temperature) on the tensile strength of PLA specimens were systematically investigated. Variance analysis and parameter optimization were performed using Design-Expert software, leading to the determination and validation of the optimal process parameter combination. The results showed that the optimal mechanical properties of FDM-printed specimens was achieved with a printing layer thickness of 0.2 mm, a printing orientation of 70°, an infilling density of 70%, and a printing temperature of 200 ℃.