Accurate prediction of land use /cover change and its impact on regional carbon reserves is of great significance to land use decision-making and climate change research. Based on the map of land use /cover in 2000 and 2012,the CA-Markov model was used to simulate the trend of land use change in 2024,and using the method provided by the 2006 IPCC Guidelines for National Greenhouse Gas Inventories,impacts of land use change on carbon stocks were assessed in the middle reaches of Heihe River during 2000-2024. Results showed that the area of arable land,grassland,construction land and woodland showed an increasing trend,while other land and water area showed a decreasing trend from 2000 to 2012. Land use /cover changes resulted in an increase of 3.22*10~6 t in carbon stocks from 2000 to 2012. The result of land use prediction showed that compared with 2012,the proportion of arable land,construction land,the woodland in total area in 2024 increased by 3.18%,0.84% and 0.77%, respectively. At the same time,water area,grassland and other land decreased by 0.33%,1.13% and 3.32%,respectively. Land use /cover changes resulted in an increase of 7.55*10~6 t in carbon stocks from 2012 to 2024,changes of different land use types led to more significant changes in carbon stocks,changes of arable land and woodland led to the main increase of carbon storage,and construction land was the main carbon producing source. Overall, the arable land,construction land,and woodland will continue to show an increasing trend,other land and water area will continue to show a decreasing trend from 2012 to 2024,and the capability of carbon sequestration is more obvious in 2012-2024 than 2000-2012.