By using the IBIS, a dynamic vegetation model, this study firstly simulated the NPP dynamics of China's potential vegetation in the past 50 years (1961-2010). Then according to the Fifth Assessment Report by IPCC, this study used the average climate conditions during 1986- 2005 as the "standard climate", and took the NPP of the potential vegetation in this climate condition as the evaluation basis. Compared with the evaluation basis, the NPP fluctuation of each year was calculated to judge whether the potential vegetation adapts the climate change or not. Meanwhile, the degree of the inadaptability was evaluated. Finally, the NPP vulnerability of potential vegetation was evaluated by synthesizing the times and degrees of inadaptability to the climate change during the past 50 years. Results showed that: the NPP of the desert ecosystems south of the Tianshan Mountains, and the NPP of grassland ecosystems in northern China and western Tibetan Plateau were more likely to be impacted by the climate change in the study period. The NPP vulnerability of these ecosystems to climate change in the past 50 years was relatively high. The NPP of most of the forest ecosystems was not likely to be influenced by climate change. The NPP vulnerability to climate change of the evergreen broadleaved forests and coniferous forests was lower. Additionally, the NPP of the desert ecosystems north of Tianshan Mountains, and the NPP of the grassland ecosystems in the central and eastern parts of the Tibetan Plateau had lower vulnerability to climate change.