Objective: To solve the problems of low dehydration rate of solidliquid separation device and discharge not free of kitchen waste. Methods: By Optimizing the parameters of the key parts of the solid-liquid separation device, modeling the solid-liquid separation device based on Creo, analyzing the extrusion process through EDEM simulation software, the optimized screw shaft prototype was made and verified. Results: The optimized spiral shaft structure parameters were conveying distance 373 mm, compression distance 180 mm, compression end diameter 96 mm, spiral blade diameter 98 mm and axis length 553 mm; the force range of solid-liquid separation device was 2.7~4.5 N, wtih average force of 3 N, and discharge speed range of 1.3 ~ 4.7 m/s with average speed of 1.9 m/s. Conclusion: The dehydration rate of kitchen waste solid-liquid separation device is significantly improved, the discharge is smooth, and the dehydration effect is better than that before optimization.