Abstract: Based on the modified carbon density in Qilian Mountain National Nature Reserve,the temporal and spatial evolution characteristics of ecosystem carbon stocks during 2000-2020 were analyzed by using InVEST model and optimal parameter geodetector,and the influence of ecosystem conversion on carbon stocks and the driving factors and mechanisms of spatial and temporal differentiation of carbon stocks were discussed.The results showed as follows:(1)From 2000 to 2020,carbon storage continued to increase,with a cumulative absorption of 132.28Tg,and the spatial distribution was relatively stable,showing a “high in the east and low in the west”,and the hot spots were distributed in the eastern and central parts of the study area in a patchy way;(2)The conversion of land use type promoted the increase of carbon storage by 141.36Tg.The conversion of grassland to forest land and unused land to water area was the dominant type of carbon storage increase.However,the scale of conversion of forest land to grassland and grassland to unused land was continuously expanding,and the risk of carbon storage loss was further aggravated;(3)Elevation,slope and population are the main driving factors affecting carbon storage,and the relationship between the two factors is double factor enhancement;(4)There are obvious differences in carbon reserves at different altitudes and gradients.The low altitude (1 750~2 400m) region has lower carbon reserves,while the middle altitude (2 400~3 500m) region has higher carbon reserves.However,due to the strong interference of human activities,the carbon reserves in this region are reduced in a dot pattern.In areas with slopes below 10°,land use conversion is frequent,vegetation is fragmented in many places,and carbon density is small.In areas with slopes above 20°,soil erosion is serious,habitat is fragile,and carbon storage is small.It is urgent to strengthen the response measures to climate change.Promote the quality and efficiency of carbon storage as a whole.