This study explores the spatiotemporal distribution characteristics and source-sink transformation processes of organic and inorganic carbon in the surface soils of northern and central Ningxia.By collecting data and conducting field sampling，carbon content data for surface soils （0–20 cm）in the region were obtained for three time periods：1980， 2010，and 2023.These data were combined with environmental datasets，including remote sensing and meteorological data， and analyzed using machine learning and GIS technologies.A systematic evaluation of the spatial distribution and temporal changes in the soil organic and inorganic carbon pools over the past 40 years was conducted.The results reveal that from 1980 to 2023，the soil organic carbon stock underwent a significant initial decline followed by recovery，with a net cumulative loss of 9.29 Mt.Between 2010 and 2023，inorganic carbon predominantly exhibited characteristics of a carbon sink，with the stock increasing by 6.35 Mt.The spatial distribution of soil organic carbon density remained relatively stable， concentrated in regions such as the Yellow River plains，Tongxin County plain，Helan Mountain area，and Luoshan area.Conversely，inorganic carbon density was higher in arid and grassland regions.Comprehensive analysis indicates regional differences in the source-sink transformation of surface soil carbon in northern and central Ningxia.Future research should focus on developing regional carbon cycle models to support carbon sink management and the sustainable utilization of land resources.