Based on the SBM-DEA model with effective efficiency frontier(optimistic)and inefficiency frontier(pessimistic), the agricultural water use efficiency of China's 31 provinces(municipalities and autonomous regions)from 2003 to 2017 is evaluated, and the Tobit model is used to analyze its influencing factors. The results show that the optimistic efficiency of China's agricultural water use has a small increase trend, and the pessimistic efficiency exhibits a decrease-increase-decrease-increase trend. The overall efficiency is not high. The difference in water use efficiency between different agricultural water zones is small. The high agricultural water use area has the highest agricultural water use efficiency, the middle agricultural water use area has the middle agricultural water use efficiency, and the low agricultural water use area has the lowest agricultural water use efficiency. The proportion of the value added of the primary industry in the regional GDP, the water-saving irrigation technology and the total storage capacity of reservoirs significantly positively correlate with the agricultural water use efficiency. While the endowment of water resources and regional education level significantly negatively correlate with the agricultural water use efficiency.