Abstract: [Objective] The the Upper Yalongjiang River basin are situated on the southeastern margin of the Bayan Har Block, characterized by a well-developed river system where large-scale NW trending active faults traverse the drainage basins, with tectonic activity constraining regional fluvial geomorphic development and evolution. Current research has predominantly focused on fault activity, paleoseismic events, and seismic hazard assessment, while studies addressing basin-scale geomorphic characteristics and their response to tectonic deformation remain relatively limited. [Methods] Based on a 30-meter resolution Copernicus Digital Elevation Model (DEM), 98 sub-basins were extracted from the Upper Yalongjiang River Basin. Five geomorphic indices were calculated for each sub-basin: hypsometric integral (HI), basin shape index (BS), asymmetry factor (AF), elongation ratio (Re), and normalized stream gradient index (SLK). These indices were quantified, classified, and integrated into a composite indicator—the index of relative active tectonics (Iat). Furthermore, by incorporating the normalized channel steepness index (Ksn) and knickpoints, the spatial differentiation of fluvial geomorphic characteristics was revealed, and the coupling relationship between tectonic activity and landscape evolution was explored. [Results] In the upper Yalong River Basin, HI values range from 0.09 to 0.63, with some sub-basins in an early stage of development and exhibiting significant structural asymmetry. Left-lateral offsets of waterways, gullies, and alluvial fans are observed. SLK and Ksn indicate strong tectonic uplift in most basins, accompanied by significant longitudinal variations in channel slope. Spatially, the Iat displays a pattern of alternating high and low values, with interconnected low-activity zones. High-Iat basins are distributed in linear belts along fault zones. Along the Wudaoliang–Changshagongma fault, which crosses the upper basin, Iat values are higher in the northern and southern Holocene-active segments, while the middle segment intersecting the Changshagongma Basin shows lower Iat values, possibly related to localized variations in tectonic deformation along fault segments. Basins traversed by the Ganzi–Yushu fault also exhibit relatively high Iat values, corresponding to strong activity at the block boundary. [Conclusion] The strong consistency among tectonic activity, geomorphic features, and seismic activity in the study area directly reflects the role of tectonic processes in shaping the regional landscape pattern. The spatial differentiation of Iat and geomorphic indices effectively captures differential tectonic uplift and deformation along fault zones, providing clear geomorphic evidence of ongoing tectonic dynamics on the southeastern margin of the Bayan Har Block.