Abstract: As a main component of the crop evapotranspiration, soil evaporation is usually useless water consumption at agriculture water use. So, it is necessary to reduce the soil evaporation as far as possible to improve the agriculture water use efficiency. In this paper, the observed field data of summer maize for two consecutive years were used to calibrate and validate the dual crop coefficients model-SIMDual_Kc model, and the observed soil evaporations measured by micro-lysimeter were also compared with simulated results of the SIMDual_Kc model. The ratio of the soil evaporation on the crop evapotranspiration was calculated and analyzed. Results show that the SIMDual_Kc model can be well applied to this region for simulating and calculating the soil water content and crop evapotranspiration of the summer maize, which has higher correlation and lower error between the simulated and observed ones. Thus the simulated values can be used for interpolation of the missing observed data and verification of the precision. It also revealed that precipitation during the initial period had a great influence on the soil evaporation, and the ratio of the soil evaporation of summer maize on actual crop evapotranspiration ranging from 37% to 45%.