The responses of dryland ecosystems are sensitive and complex to climate change. The environment of the pastures is more vulnerable because of the grazing effect and the frequent human disturbance. Moreover,due to the fields data insufficiency for the area,the carbon dynamic of dryland ecosystem,especially the spatiotemporal patterns,are still unclear. Using the modified Biome-BGC grazing model,we assessed patterns of carbon dynamics in Xinjiang from 1981 to 2007 in different scenarios. The results indicated that in the past 27 years, Xinjiang acted as a C sink of 59Tg(1Tg = 10~(12)g). The VEGC sequestration WAs comparable to the soc,accounted for 43. 04% and 43. 08% of the total carbon sequestration,respectively. The grazing resulted in 20. 58Tg of C loss,while CO_2 fertilization effect resulted in 64. 29Tg of C sink. Climate change resulted in 9. 52Tg of C loss. In the mid 1980s,the VEGC of the pastures decreased significantly and might have much to do with the protracted drought,but the SOC were affected slightly. This study described the spatiotemporal patterns of carbon dynamics of dryland ecosystem clearly and offered some suggestions for the follow-up study in this field.