By collecting the atmospheric precipitation, surface water, and groundwater in the Inner Mongolia section of the Yellow River Basin in July 2021 (wet season), October (normal season), and April 2022 (dry season), stable isotope technology was used to analyze the temporal and spatial changes in hydrogen and oxygen stable isotopes in the "three rivers" of the basin, and the MixSIAR mixing model was used to reveal the water body transformation relationship. The results showed that the mean difference in the groundwater isotope was small in the abundance period, flat period, and dry period in the Mongolia section of the Yellow River Basin. The groundwater regeneration was slow, the retention time was long, the seasonal variation was not obvious, and the