Abstract: Based on field investigation and remote sensing information, this paper carried out both qualitative and quantitative analyses of the characteristics of ecosystems in Ndong County of Tibet. Then taking erosion degree, function lacking degree and productivity level as evaluation indices, the authors assessed the different kinds of ecosystems and divided them into four types: healthy, less healthy, less unhealthy and unhealthy. The authors also pointed out that at present, the main ecological types in Ndong County are sub-healthy and sub-unhealthy ecosystem. Unhealthy systems spot in the sub-healthy and sub-unhealthy ecological systems. It also put the scientific foundation for the sustainable development of ecological social economy system of Ndong County. And it draw the conclusions; (1) Using the intensity of corrosion, the level of the productivity and the function decrease as the indices of evaluation can factually reflect the health condition of Ndong County. (2) At present the main ecological types in the Ndong County are sub-healthy and the sub-unhealthy ecosystem, the intensity of human disturbance must be decided according to the health condition. (3) Unhealthy systems of Ndong County spotted in the sub-healthy and sub-unhealthy ecological systems. As long as human can control effectively, it will not diffuse on a large scale, and can recover step by step.