Under the coupling effects of climate change and human activities，the carbon cycles of the steppe eco-system have changed significantly. This paper introduced the background and importance of the grassland carbon cycle，and then presented the domestic and overseas’ grassland carbon cycle research progress，including discussions of carbon source and carbon sinks，the research status of soil respiration，the influence of climate change and human ac- tivities on the grassland carbon cycles，the main technology methods，as well as some important results and conclu- sions in studying grassland carbon cycle detailed. On this basis，deficiencies and problems，existing in the research of the grassland carbon cycle，were analyzed，future research prospects were expounded，and the key research directions were put forward，so as to provide a theoretical basis for the research of the terrestrial ecosystem carbon cycle in the context of “dual carbon” goal.