Abstract: Ecological function regionalization is of great importance in ensuring regional ecological security and promoting the coordinated development of economic, social and ecological environment. The Upper Yangtze River is such an important ecological security barrier for the key ecological areas of China and the whole Yangtze River Basin that it is very important to carry out its ecological function regionalization. Taking the Upper Yangtze River as the study area, this paper focuses on revealing the spatial pattern of the ecological environment sensitivity and the ecosystem service function by utilizing GIS spatial analysis technologies. Moreover, with the sub basin as the basic division unit, the Upper Yangtze River zones were implemented using the two step clustering method. The results showed that:(1) The ecological environment in the Upper Yangtze River was in a moderate and highly sensitive condition, while the sensitivity of soil erosion was the most prominent. (2) The ecosystem service function in the Upper Yangtze River showed a relatively important and very important situation, while the water conservation and biodiversity conservation were more important. (3) The Upper Yangtze River can be divided into three ecological areas, which are the Qinghai Tibet plateau ecological area, the Yunnan Guizhou plateau ecological area and the Sichuan basin ecological area, which can be further subdivided into seven ecological sub-regions and fifteen ecological function regions.