In this study,the effects of nitrogen,phosphorus and potassium application on yield and starch content of potato plants were investigated by 311A regression design in rainfed agricultural area in Ningxia province.Mathematic models between yield and starch content and the parameters of nitrogen,phosphorus and potassium amount used were built.Meanwhile,the main factor and interaction factor affected yield and starch content were analyzed.The results showed that the optimum nitrogen,phosphorus and potassium application amount to acquire the highest yield was 267.3,139.0 and 82.1 kg/hm2,respectively,to acquire the highest economic value was 258.6,131.1 and 71.1 kg/hm2,respectively,to acquire the highest starch content was 183.9,106.4 and 87.6 kg/hm2,respectively.