According to the enterprise actual demand, the static and dynamic characteristics, lightweight analysis of smooth pillow structure of a certain type of double tauren EDM machine were studied. In the situation of material and structure size constraints, based on improvement on unreasonable reinforcing plate structure and main size parameters sensitivity analysis, optimization design model was gotten. The simulation analysis results show that the optimized model ensures static and dynamic characteristics, and has obvious lightweight effect, weight loss amounts to 12.07%.