SThe formation mechanism of multi-source braided rivers is challenging to quantify due to the frequent, rapid, and continuous migration and interaction of channels, influenced by factors such as paleo-topography, sediment supply, and hydrodynamic conditions. This results in the constant growth and dissection of mid-channel bars. To investigate the interactive evolution process of multiple braided rivers under different paleo-topographic, hydrodynamic, and sediment supply conditions, this study is based on the source-to-sink characteristics of the multi-source braided rivers in the lower Shihezi Formation of the Xinzhao area in the Ordos Basin. A flume experiment was designed with three distinct topographic zones: valley, slope-break, and gentle slope. Additionally, hydrodynamic conditions and sediment supply rates were set as variables. Three sets of experiments were conducted to quantitatively analyze the impact of these variables on the interactive evolution process of multi-source braided rivers. Each set of experiments was designed with 21, 22, and 10 phases of braided channel deposition experiments respectively, lasting a total of 102 hours. A 3D laser scanner was used for precise sedimentary geomorphology monitoring and quantitative sedimentological analysis to study the depositional evolution process of multi-source braided rivers. The results indicate:1)The evolutionary models of channel bars in valley regions can be classified into four end-member types: accretion-erosion-migration bars, accretion-erosion-accretion-erosion bars, stable accretion bars, and stable stagnation bars. 2)Under multi-source conditions, braided river deposits exhibit pronounced differentiation: under uniform sediment supply, sand bodies thin toward the depositional axis; under varying hydrodynamic conditions, slope-break and gentle slope regions form a "left-network, right-bar" configuration (anastomosing channels on the left, isolated bars on the right); with differential sediment supply rates, low-supply braided channels evolve into single-thread, straight channels, leading to laterally homogeneous sandbody distributions.3)Channel bars exhibit length-to-width ratios ranging from 2 to 5, averaging 2.5. In valley regions, steep topographic gradients and strong hydrodynamic forces enhance vertical incision, inhibiting channel bifurcation, while abundant sediment supply promotes the development of longitudinal channel bars aligned parallel to the valley axis. In slope-break zones, reduced basal slopes and weakened hydrodynamics facilitate channel branching, forming composite bars through amalgamation of isolated bars, where two adjacent fluvial systems interact, resulting in widened channel belts. In gentle slope regions, minimal basal slopes and low hydrodynamic energy favor the preservation of isolated bars. 4)Basal slope is the primary control on channel bar density, with lower slopes correlating to higher bar densities. 5)Basal slope, hydrodynamic intensity, and sediment supply rate synergistically govern bar scale and abundance: under reduced hydrodynamic intensity, valley regions exhibit increased bar scale and abundance, slope-break zones show decreased bar scale but increased abundance, and gentle slopes display decreased bar scale and abundance; under reduced sediment supply, valley regions experience decreased bar scale and abundance, slope-break zones exhibit decreased bar scale but increased abundance, while gentle slopes develop increased bar scale but decreased abundance.