Abstract: Based on irrigation experiment data of 4422 station years taken from 22 provinces for 10 kinds of main grain crops from 1980 to 1986, average water use efficiency(WUE) of grain crops in irrigated farmland in China was set as about 1.1 kg/m³ with weighed average method. It was concluded that the value of 1.1 kg/m³ is acceptable to be as present value of average WUE of main grain crops in irrigated farmland in China, through comprehensive analysis on the relations between crop yields and WUE, total water consumption and WUE at typical experimental station, and on the changing trend of average yield of main grain crops with years nationwide.