Abstract: The changes and relationship of water use efficiency(WUE) at different levels of winter wheat were studied in detail by designing different irrigation treatments. The results showed: the WUE at leaf level or transpiration efficiency (TE) was the basis of evapotranspiration efficiency (ETE). The mechanism of stoma and the differences of the correspondence of photosynthesis and transpiration to environmental changes were the physiological basis of WUE at leaf level. The WUE at yield level was determined by evapotranspiration efficiency (ETE) and harvest index (HI). Photosynthesis rate, dry matter accumulation of population and grain yield had a quadratic relationship with crop water consumption, which resulted in a linear decrease on WUE at leaf and population levels and quadratic changes in WUE at yield level. The WUE at different levels of winter wheat had a great variation in values and changes caused by crop water consumption.