Abstract: Abstract: Objective The hilly and gully region of the Loess Plateau is one of the most erosion-prone areas in China, where gully erosion plays an important role in landscape dissection, sediment production, and land degradation. Although previous studies have examined gully morphology and distribution at regional, hillslope, and individual-gully scales, gully developmental stage and potential at the micro-watershed scale remain poorly understood, especially along the north-south transect. Therefore, this study aimed to quantify gully developmental stages and development potential in typical micro-watersheds, compare their spatial differences along the transect, and provide a basis for gully erosion control and soil and water conservation on the Loess Plateau. Methods A total of 82 typical micro-watersheds near drainage divides were selected from seven representative sampling areas along a north-south transect in the hilly and gully region of the Loess Plateau. High-resolution topographic data were obtained using unmanned aerial vehicle (UAV) photogrammetry, and 1 m digital elevation models (DEMs) were generated through aerial triangulation, point-cloud filtering, and terrain reconstruction. Gully edge lines were delineated by visual interpretation based on DEMs, slope maps, hillshade maps, and high-resolution orthophotos. The areas and mean slopes of gully land and interfluve land were then extracted for each micro-watershed. Gully developmental stage was quantified using the hypsometric integral (HI) and hypsometric curves, while gully development potential was evaluated using slope-area (S-A) threshold analysis. To assess the influence of land use, the micro-watersheds were further classified into cropland-dominated and woodland-dominated types according to the dominant land use in the interfluve area, and separate threshold relationships were established in logarithmic space. Results (1) Micro-watersheds along the transect exhibit a distinct pattern of “high activity in the central sector and constrained or differentiated conditions in the northern and southern sectors.” The central sector is characterized by a smaller interfluve-area proportion and stronger gully incision activity, whereas the northern and southern sectors show larger interfluve-area proportions and gentler mean slopes, indicating relatively stable systems with only localized high-activity units. (2) HI values display a “high–low–high” trend from north to south; 85% of micro-watersheds in the northern and southern sectors are in the mature stage. Hypsometric curves are predominantly S-shaped, indicating a stage dominated by active incision and lateral expansion. (3) Slope–area (S–A) analysis indicates that cropland-dominated micro-watersheds have larger contributing (drainage) areas than woodland-dominated ones, implying higher development potential; moreover, management measures that reduce local slope gradients adjacent to gully edges can lower gully development potential. Conclusions Coupling HI with the S-A threshold provides an effective framework for evaluating gully developmental stage and potential at the micro-watershed scale. Overall, the hilly and gully region of the Loess Plateau is mainly in a mature geomorphic stage, with clear spatial differentiation along the north-south transect. The central region shows stronger incision activity and geomorphic adjustment, whereas the northern and southern regions retain larger interfluve areas and more heterogeneous developmental conditions. In general, more advanced geomorphic development is associated with more active gully development and greater potential, providing a scientific basis for identifying priority areas for gully erosion control and developing region-specific soil and water conservation strategies.