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Climate change and its effects on grassland productivity and potential carrying capacity of livestock were systemically studied using AVIM-GRASS and other models, using daily meteorological data for the period from 1961 to 2007 for 70% (275 million ha) of grasslands across China. The results showed an overall trend for increasing temperatures per year and in the length of the grass-growing season from April to September. Sunlight hours decreased in most places. Precipitation and a humidity index had decreased in the northern grasslands of China, where the climate has become warmer and drier, and had increased in the western grasslands, where the climate has become warmer and wetter. Changes to a warmer and drier climate in the more productive northern grasslands resulted in a decrease in annual available herbage production and the carrying capacity of livestock. The greatest reductions in productivity have been in middle and east Inner Mongolia and south-east Gansu. Where there had been a trend for a warmer and wetter climate in western grassland areas, the trend in available herbage production and carrying capacity of livestock has been for a small increase or none at all. The largest rate of increase in productivity was in south-west Xinjiang and east Xizang. Annual available herbage production and carrying capacity of livestock decreased in north and east Xinjiang and south Qinghai where there was very little increase in precipitation. Overall, climate change has resulted in an average decrease in annual available herbage production and carrying capacity of livestock in most of the main grassland areas in China from 1961 to 2007.