Abstract: Climate change and elevated CO2 concentration have significantly influenced on the Spatiotemporal distribution of global and regional grassland carbon storage. To detect the effects of present and future climate scenarios on spatiotemporal distribution of NEP and analysis the main factors of grassland NEP, this study used the CENTURY model after parameter calibration to estimate the values of net ecosystem production (NEP) from 2000 to 2014. The one-way ANOVA and error analysis were used to verify the model. The SSP126, SSP245 and SSP585 as the future climate scenarios also be used to simulate the spatiotemporal change of the NEP from 2015 to 2100. The results show that there was a good agreement between the observed and predicted NEP; The inter-annual variation of NEP decreased year by year under different scenarios. The northwest and eastern of Gansu province are sensitive areas to NEP spatial change. Precipitation, longitude and temperature were significantly positively correlated with NEP, which is significantly negatively correlated with temperature, but weakly correlated with precipitation. In addition, increased CO2 concentration was positively correlated with NEP. The annual average changes of grassland NEP in Gansu under the SSP126, SSP245 and SSP585 climate scenarios are 595.95 gC·m-2·a-1、604.53 gC·m-2·a-1 and 679.17 gC·m-2·a-1, respectively. During 2019-2048, grassland NEP decreased at a rate of -0.69 gC·m-2·a-1 (P<0.01) in the SSP126 climate scenario, no significant changes in the SSP245 climate scenario at a rate of -0.2 gC·m-2·a-1, and increased significantly at a rate of 1.36 gC·m-2·a-1 (P<0.01) in the SSP585 climate scenario. On average, grassland in Gansu is a carbon sink under different[ climate scenarios, and the potential carbon sequestration capacity of grassland will gradually increase under future climate change.