Abstract: By field comparing trail on proportion of N,P,K, and density of Mengpiyihao barley in Hetao irrigated area of Inner Mongolia, a 4-factor and 2-degree regression model was set up, which can offer the theoretical basic for high quality and high yield of Mengpiyihao barley in Hetao irrigated area. The Results showed there was a obvious effect on yield by rational application of N,P,K and Density. According to mathematic model, when N：8.0000kg/667m^2,P2O5：8.0000kg/667m^2, K2O： 2.5000kg/667m^2,sown seed amount： 21.1261kg/667m^2 （50g/1000seeds）, the highest yield can reach to 723.2109kg/667m^2 .When N： 7.093kg/667m^2,P2O5：3.730kg/667m^2, K2O：4.580kg/667m^2,sown seed amount： 20.520kg/667m^2 （50g/1000seeds）, the optimum yield was 549.7956 kg/666m^2.