In order to construct the high spatial-temporal dataset of evapotranspiration (ET), the Landsat and MODIS data were used to achieve spatial downscaling of ET by using the enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM). The result of data fusion was evaluated by field ET output from root zone water balance model. According to crop planting structure information from 2000 to 2015 in the study area, the water consumption of different crops was exacted during their growth and non-growth periods. Based on the fusion ET, the interannual variation of total agricultural water consumption was analyzed since the implement of water-saving project in large irrigation district. The result showed that the process of fusion ET was more consistent with ET output from water balance. In the correlation analysis of water balance and fusion ET, the determination coefficients (R2) of maize, wheat and sunflower reached 0.85, 0.79 and 0.82, respectively. During the growth period, the root mean square errors (RMSE) of maize (May to October), wheat (April to October) and sunflower (June to October) were lower than 0.70mm/d, the mean absolute error (MAD) was all lower than 0.75mm/d, and the relative error (RE) was all less than 16%. On the spatial scale, the spatial characteristics of fusion results were consistent with the Landsat ET. The correlation coefficients of July 23, August 24 and September 1 reached 0.85, 0.81 and 0.77, the mean values of the differences were 0.24mm, 0.19mm and 0.22mm, and the standard deviations were 0.81mm, 0.72mm and 0.61mm, respectively. The high resolution ET based on ESTARFM fusion algorithm was reliable and had good fusion precision. The water consumption of different crops varied greatly both in the growth period and non-growth period. During the growth period, the maximum water consumption was 637mm for interplanting (April to October), followed by maize and sunflower, which were 598mm (May to October) and 502mm (June to October), respectively, the minimum water consumption of wheat was 412mm (April to July). During the non-growth period, wheat (August to October) had the highest water consumption with an annual average of 214mm, and those of maize (April) and sunflower (April to May) were 42mm and 128mm, respectively. Due to the difference of average annual water consumption of different crops was not significant during April to October, the variation of total water consumption for different crops was varied with the changes of crop acreage.