Abstract: The relationship between the changes of sink-source and water use efficiency (WUE)in wheat(Triticum aestivunt L)was studied under the conditions of increasing the ratio of sink／source by cutting leaves and changing grain number of male sterile and male fertile line．Th results showed that the ratio of sink／source．grain number and photosynthetic rate are positive in relevant with WUE．Enlarging sink capacity by increasing grain number and grain weight and raising source supply ability by strengthening the leaf activity coold increase yield，resulting in high WUE．