Abstract: In order to solve problems of poor flavor, serious damage of texture and great loss of nutrition, potato mud making process and equipment were optimized．Based on principle of spiral extrusion, a groove cavity and a variable pitch screw were designed, and extrusion machine tests were carried out to test effects of different mud making processes on nutritional composition, flavor and texture of potato mud．Results showed that quality of mashed potato was the best when potato chip thickness was 1.0 cm, steam was 11 min and pressure was 0.01−0.20 MPa．At the same time, combined with physical and chemical characteristics of potato mud, quality evaluation index system of potato mud was improved．Simulation results showed that combination of groove cavity with variable pitch screw has the best crushing effect, and design of orifice plate outlet structure was stable and uniform．With increase of screw speed or feed speed, pressure in extrusion section cavity and outer cylinder of orifice plate increased．Test results showed that potato mash produced by screw extrusion was soft and delicate, with strong flavor, little nutritional loss, and product quality was significantly improved．