Abstract: Soil samples were collected from upper and lower slope positions at two depths (0~20 cm and 20~40 cm) within runoff plots (corn) of 5°, 10°, 15°, 20°, and 25° slopes in the Fugou small watershed, Wanzhou District, Chongqing. This study aimed to elucidate the spatial heterogeneity patterns and driving mechanisms of soil stoichiometric characteristics on sloping farmland in the Purple soil region. Key findings include: (1) Slope gradient, slope position, soil depth, and their interactions exerted highly significant effects (P<0.001) on soil mechanical composition. Silt particles dominated (52.72%~72.20%) the runoff plot soils, with pH ranging from 7.12 to 8.05. (2) Within the 0~40 cm soil layer, soil organic carbon (SOC) and total nitrogen (TN) contents followed the order: 25° > 5° > 20° > 15° (10°) > 10° (15°). In 10~25 ° runoff plots, the SOC and TN contents in the surface layer (0~20 cm) changed regularly with the slope, and decreased with the deepening of the soil layer. (3) Soil C/N ratios across the 0~40 cm layer ranked as: 15° > 25° > 5° > 20° > 10°. At the lower slope position, surface soil C/P and N/P ratios showed positive correlations with slope gradient. Notably, the 10° runoff plot exhibited 37.07% and 30.00% increases in C/P and N/P ratios respectively, compared to the 25° runoff plot (P<0.05).(4) Runoff volume and sediment yield initially increased and then decreased with increasing slope, peaking at the 20° runoff plot, which also experienced the most severe erosion-deposition. (5) Significant positive correlations were identified within the 0~40 cm layer: SOC with TN; Both SOC and TN with total phosphorus (TP), C/P, N/P, and silt contents (P<0.05); and surface runoff volume with both C/P and N/P ratios (P<0.05). Sampling location was the dominant factor explaining variation in SOC (35.5%) and TN (37.4%), while soil physicochemical properties primarily governed variation in C/N (25.9%) and C/P (22.1%) ratios. Soil C/N, C/P, and N/P ratios in these runoff plots were lower than the national averages, indicating nitrogen as a potential limiting factor. The 15°~20° slopes range likely represents an erosion-deposition equilibrium gradient. Given its minimal erosion intensity and high soil nutrient availability, the 10° slope is recommended as the priority gradient for maize cultivation in this region.