North Tibet alpine prairie is the core region to the development of Tibet stockbreeding. Grassland degradation has become more and more serious and restricted the sustainable development of Tibet economy. Under the background of the global-change, there is a deteriorating tendency in the degradation of the grassland ecosystem due to the increasing intensity and frequency of human interferences, together with the rigorous natural environment and the frangible ecosystem. This paper explores thoroughly the degradation mechanism of north Tibet grassland ecosystem after a detailed description of the current degradation situation.