The hydro logical elements——precipi tation, runoff,and evapotranspirationwith different elevation give different distributional regularity. For middle or small region scale (such as a middle or small watershed, a high hill) the amount of precipitation or runoff increases with elevation and the amount of evapotranspiration decreases with elevation, Forlarge region scale (such as a large watershed or a large mountain range) the amount of each hydrological element decreases with elevation. Using this principle of spatial hydrology, the problems on scarce gauging station in moutain areas and distribution of hydrological elements with orographic influences can he solved.In the paper there are four parts to be researched:1. Relationship between annual rainfall and elevation, 2. Relationship between annual evapotrans-piration and elevation. 3. Relationship between annual runoff and elevation; and 4 The application on the conception of spatial hydrology.The results of these studies have been applied in streamflow assessment in the western part of China, where hydrologic data are incomplete or lacking. In the southern part of Tibet, after assessing, streamflow increased about 900 million cubic meters as compared with the primary result of that region.