The principle of cow dung press is spiral extrusion solid-liquid separation technology. The main components are: body, screen, extrusion auger, reduction motor, discharge device and other components. The solid separated from the cow dung dehydrator is dry and odorless. It is a good farmland fertilizer. It does not produce leachate during storage, and is convenient for transportation and storage. It can effectively improve the air environment of the livestock farm and solve the environmental pollution problem during the transportation of solid dung residue. After separation, the water content of the liquid part is about 60%, which is not easy to produce crusting and sedimentation during storage. The separated liquid nitrogen and phosphorus content is small, which can be diluted and used as irrigation water or fertilizer, and can be effectively absorbed by farmland crops.