The Southwest Alpine Canyon Area of China exhibits pronounced soil erosion differentiation and complex erosion patterns due to steep terrain, variable climate, and multiple erosional drivers, posing significant challenges to local ecological sustainability. To scientifically assess soil erosion risks and formulate mitigation strategies, this study established a three-dimensional risk assessment framework integrating erosion hazard, landscape vulnerability, and potential ecosystem loss. The Revised Universal Soil Loss Equation (RUSLE) coupled with a freeze-thaw erosion model was employed to evaluate erosion hazard, while landscape pattern indices and the InVEST model were utilized to quantify vulnerability and potential loss. The spatiotemporal evolution of soil erosion risks from 2000 to 2020 was systematically analyzed, and targeted management measures were proposed. Key findings include: (1) Hydraulic and freeze-thaw erosion accounted for 69.98% and 30.02% of total erosion area, respectively, forming a distinct spatial pattern dominated by hydraulic erosion in the south and freeze-thaw erosion in the north. Hydraulic erosion primarily occurred at mild intensity (69.38%), whereas freeze-thaw erosion was predominantly light (50.15%) and moderate (33.69%).(2) Overall soil erosion risk remains relatively low, with 87.42% of the region classified as low and medium-low risk. Spatially, higher risks were concentrated in the northwest-southeast regions and exhibited localized aggregation with global dispersion. Over the past two decades, soil erosion risk showed an increasing trend, followed by a period of decline, but the overall trend was still upwards. The medium- or high-risk areas increased by 34.49%, but the rate of increase slowed down over the past decade. (3) The Eastern Tibet-Western Sichuan Alpine Canyon Ecological Conservation and Water Retention Zone (Zone Ⅱ) experienced the most pronounced risk escalation, while the Northern Yunnan-Western Sichuan Alpine Canyon Soil and Water Conservation Zone (Zone Ⅲ) showed the highest transition rate of medium-to-high risk areas, with over 50% of zones shifting to higher risk levels, marking these as critical hotspots. This study underscores the diversity of soil erosion risks in southwestern alpine canyons. Future efforts should prioritize ecological stability in low-risk zones to mitigate potential degradation while implementing region-specific restoration strategies in high-risk areas to rehabilitate degraded ecosystems and ensure regional ecological sustainability.