Carex moorcroftii, one of the most widespread dominant species on the Qinghai-Tibetan Plateau, plays important roles in water and soil conservation of the plateau. MaxEnt (maximum-entropy) model was employed to simulate the significant climatic factors influencing the distribution of Carex moorcroftii, and to predict the change of distribution range in past and future climate scenarios. The results showed that: (1) Max temperature of warmest month (Bio5), mean temperature of warmest quarter (Bio10), standard difference of temperature seasonality (Bio_4) were the most significant factors determining C. moorcroftii's suitable habitat, ranging from 6.7 to 21.3°C, from -0.8 to 14.3°C, from 5.3 to 10.1°C respectively. (2) North Tibet core area of South Qiangtang and Hoh Xil were the most suitable areas of C. moorcroftii on this plateau. (3) From Last Glacial Maximum (LGM) to present, the suitable areas of C. moorcroftii decreased by 10.1%, and the average distribution altitude increased by 467 m; and from present to the future (2050), the suitable area would decrease by 32.7%, and the distribution altitude would increase by 201 m.