In order to evaluate the characteristics of soil erosion and its driving factors in the Xiaolangdi Reservoir area in the past 30 years, this study estimated the soil erosion modulus in the Xiaolangdi Reservoir area from 1990 to 2020 based on the Revised Universal Soil Loss Equation (RUSLE), and analyzed the spatial-temporal variation characteristics of soil erosion. Then combined with geographic detector, the effects of vegetation coverage, land use type, altitude, slope and rainfall on soil loss patterns were quantitatively analyzed. Results showed that: (1) The soil erosion modulus in the Xiaolangdi reservoir area decreased from 3 150 t/(km²·a) in 1990 to 1 554 t/(km²·a) in 2020, and the total soil erosion decreased by 50.00%. The intensity of soil erosion also changed from high level to lower level. From 1990 to 2020, the area of extremely severe, very severe, severe, moderate and slight erosion decreased by 53.92%, 64.51%, 55.65%, 39.68% and 3.28%, respectively. While the area of very slight erosion increased by 41.13%. At the present stage, the main erosionintensity was very slight erosion, followed by slight erosion, which accounted for 60.02% and 24.08% of the total erosion area, respectively. (2) Serious soil erosion in the Xiaolangdi Reservoir area was mainly distributed in the southwest (Pinglu County, Shanzhou District), southeast (Jiyuan City, Mengjin County) and central (Yuanqu County) of the reservoir area where human activities are concentrated, but it tended to shrink and gather in time and space. (3) Vegetation coverage and land use type had higher explanatory power than other factors, vegetation coverage could explain up to 42.09% of soil erosion, while land use type could explain up to 28.64% of soil erosion, and the interaction of different factors enhanced the explanatory power of soil erosion risk. Low altitude (< 718 m) and gentle slope (8°~16°) areas were high risk areas for soil erosion due to the high accessibility of human activities and low vegetation coverage. Ecological restoration and soil and water conservation measures in these areas should be strengthened.