The source region of the Yangtze River lies to northeast of the Northwestern Plateau in Sichuan, where is one of the most important areas of the Three-River headwaters region in China. In recent 40 years, with the alpine ecosystem and permafrost were continuingly degraded under climate warming, the frozen earth-ecological environment system in this area has changed greatly, the annual runoff decreased continuously, and the variation of the runoff had affected the function of conservation on water supply in the source region of the Yangtze River at the same time. Therefore, it is increasingly urgent to study the spatial-temporal variation of the runoff in the source region of the Yangtze River. According to the data form the hydrologic and meteorological stations as Tuotuo River, Wudaoliang, Zhiduo, Qumalai and Yushu, a multiple time scales analysis has done to reveal the annual, inter-annual and decadal variation of the precipitation and runoff. Furthermore, in according with the regional distributed character of the precipitation and runoff analysis, the calculating results show that annual runoff of the source region of the Yangtze River changed with precipitation, the runoff seasonal distribution focused from May to October and had a reduce trend, and decadal changes of runoff did not show obvious regularity. However, these results have a very important scientific value and a practical mining to the further study on the water resources security and the ecological environment in this area, the sustainable utilization of water resources in the middle and lower reaches of the river, and the security of the regional ecosystem in the Three Gorges reservoir area especially.
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