Abstract: In order to estimate the crop evapotranspiration of summer maize（Zea mays L.） in Huaibei plain more accurately, the calculate methods of the basal crop coefficient（K_cb） and the soil evaporation coefficient（K_e） in FAO dual crop coefficient approach were improved using the leaf area index data, which was measured by summer maize experiment in Wudaogou Hydrology Experimental Station in Bengbu city,Anhui province. Then the accuracy of the estimated results by FAO and improved dual crop coefficient approach was evaluated by comparing the estimated values and the observation values which were obtained by lysimeters. The results showed that the accuracy of the improved dual crop coefficient approach was higher than that of FAO dual crop coefficient approach in all growth stages and the whole growth period of summer maize. The improved dual crop coefficient approach was the most effective in the evapotranspiration calculation of summer maize between jointingstage and tasseling stage. The improved dual crop coefficient approach was more suitable for the estimation of evapotranspiration of summer maize in Huaibei plain.

Key words: summer maize（Zea mays L.）, leaf area index, crop coefficient approach, crop evapotranspiration, Huaibei plain