In this article,we firstly used daily observed data to calculate the ET0 and index of moisture of meteorological station in the Three River Headwater Region of Qinghai Province from 1966-2010 by using Penman-Monteith Model and Thornthwaite method. Then we analyzed the four climatic factors of average temperature,precipitation, the ET0 and the index of moisture for seasons and river basins. The result showed that the annual temperature of this region rose significantly. The precipitation of this region decreased in 1990s,and increased in 2000s,but not reached the level of 1980s. The index of moisture presented little range rising trend. The headwaters region of the Yangtze and Lancang River was getting warm and wet,whereas the headwaters region of the Yellow River was getting warm and dry.