Abstract: In this paper, the variance of annual rainfall in Xinjiang by variation coefficient (Cv) widely used in staticstics and hydrography is studied. Based on analysing to 25 years' observational data in 98 stations, authors found that the variation coefficient of annaal rainfall has better relation with annual rainfall and sea level elevation, which can be expressed by a bivariate function. It is valuable for this finding to research ciimatic theory and water resources in the area where data are rare urrdoubtedly.