Gonghe Basin (GB) is located in the northeast of Tibetan Plateau with semi-arid climate, it is a typical area where fluvial-aeolian interaction occurs widely and has a profound impact on aeolian processes. This study employed SBAS-InSAR technique to monitor the surface deformation caused by fluvial-aeolian interactions in a small watershed from March 2017 to December 2024. Additionally, end-member model analysis (EMMA) was applied to analysis the sand supply for aeolian activities. The results indicate that the hydrological system serving as a sediment source area shows a general trend of subsidence with an average deformation rate of -0.31 mm/a. On the contrary, the floodplain area serving as a sediments deposition area exhibits a mainly fluctuating upward deformation feature with an average deformation rate of 1.60 mm/a. Grain-size analysis shows aeolian sediments from dunes located downwind of the floodplain is dominated by fine sand, medium sand and very fine sand, followed by silt and coarse sand, with very little clay. The EMMA results reveal a transport pathway in which sediments released from Quaternary strata within the watershed to the floodplain and subsequently to dune fields through fluvial-aeolian interactions, providing a key sand supply for aeolian activities. Therefore, our findings suggest that aeolian sand hazard management should be enhanced through the integration of sand stabilization and desertification control with the interception of sediment export from watershed.