For regional social and economic sustainable development, strengthening land ecosystem management at a provincial scale is prerequisite. One of the most important tools is to identify the critical or sensitive area that is easily degraded. So here in a methodology of eco-sensitivity assessment was proposed and a case of Yunnan Province was studied. Eco-sensitivity was defined as the possibility of formation and generation of eco-environment problems in a given region influenced by natural factors. Land eco-environmental problem considered are soil erosion, stone desertification, biology diversity, geological disaster and water environment. Based on the information of eco-environmental investigation of 2003 and previous studies, we have used GIS techniques to integrate the assessments of sensitivity to the five factors. The results show that moderately sensitive areas and highly sensitive areas are dominant, the properties to the total land area are 36.67% and 46.93% respectively, and the insensitive area accounts for 10.15%, the extremely sensitive area share the smallest proportion, only accounts for 6.25%. Looked from the regional distribution that, the moderate sensitive type area has the distribution in each area of entire province, the highly sensitive area mainly distributes in the northeast and northwest of Yunnan as well as partial areas of Yunnan′s west.