Carbon cycle is an important part of the ecosystem processes. Research on mechanisms of the key processes of carbon cycle will help us better understanding the ecosystem processes. So far, climate change (global warming, the change in spatial and temporal distribution pattern of precipitation) has an important impact on grassland ecosystem processes. This article systematically reviews the effects of climate change (global warming and precipitation change) on the key processes of grassland ecosystem carbon cycle (plant productivity, plant phenology, plant root turnover, soil and ecosystem respiration, and net ecosystem C exchange). Through the review, we pointed out the deficiencies of the manipulative experiment and proposed that some researches should be strengthened in the future.