Abstract: The connotation of crop water use efficiency (WUE) was analysed in detail in this paper. The research history and development of WUE both at home and abroad was reviewed. On the basis of elaborating the concept system of WUE, the calculating models for WUE at different levels were made clear so as to further the study of WUE, which could provide the scientific basis for the high efficiency of agricultural water use and agricultural sustainable development.