Greenhouse effect caused by human activities is becoming increasingly fierce, people are paying much more attention to carbon cycle. Grassland as an important terrestrial ecosystem,it is important to study the carbon reserves. the current studies on soil organic carbon in grassland ecosystem by domestic and foreign scholars were summarized, the main factors affecting the soil organic carbon, including temperature and precipitation and other natural factors,as well as, grazing, cultivation,fertilization and other human factors were analyzed; the research results of response of grassland soil organic carbon pool to the global warming and atmospheric composition change were summarized. The future research direction of soil organic carbon in grassland was pointed out.