Water use efficiency of grain production reflects the relative changes in water use and grain output of agricultural production and is related to long-term food security as well as sustainable agricultural development. This study takes the water footprint of grain production as an indicator of water resources input，adopts the super-efficiency SBM model to scientifically measure the water use efficiency of China’s total factor grain production，and on this basis，uses the Spatial Durbin model to analyze the influencing factors and spatial spillover effects of water efficiency. The results of the study show that：① The water footprint of 31 provinces’ grain production increased by an average of 4.5% from 2001 to 2019，of which the water footprint of corn and rice showed an upward trend，and the increase was mainly seen in the central region.② The water use efficiency of regional grain production is highest in the east followed successively by the west and the middle area. The water use efficiency in the southwest region and the southern coast is higher，while in the northwest region and the Yellow River Basin is lower. Water utilization at the provincial level is spatially divided into two levels：“high water consumption with low efficiency” and “low water consumption with high efficiency”.③ Water-saving technology，water-land matching，urbanization level and fertilizer price have significant positive impact on the water use efficiency of grain production，while the impact of water resources supply structure as well as industrial structure is significantly negative. The regional heterogeneity of these factors is the main reason for the difference in the spatial distribution of water use efficiency.④ Water efficiency of grain production can be spatially correlated and spilled through technology spillover，factor flow，production agglomeration and price transmission. Based on this，it is proposed to explore the potential of water efficiency improvement，use regional mutual feedback effect，and realize the coordinated improvement of water use efficiency in grain production.