[Objective] The spatiotemporal variations of soil water erosion in the eastern region of the agro-pastoral ecotone in northern China were investigated， and the effects of multi-factor interactions on water erosion dynamics were quantified first time， in order to provide decision-making support and methodological references for soil erosion control and ecological environment restoration in this region. [Methods] Based on the RUSLE model， an attribution analysis was conducted on the spatiotemporal differentiation characteristics of soil water erosion in the eastern region of the agro-pastoral ecotone in northern China from 2000 to 2023， and a quantitative analysis was performed on the main contributing factors to dynamic changes in soil water erosion. [Results] ① The multi-year average soil water erosion modulus in the eastern region of the agro-pastoral ecotone was 777.94 t/（km²·a）， with most areas dominated by very slight and slight erosion， accounting for 69.3% and 22.9% of the total water erosion area， respectively. ② From 2000 to 2023， the soil water erosion intensity in the study area showed a slight increasing trend， with an increase rate of 0.90 t/（km²·a）. Soil water erosion alleviated in the southeastern and northwestern parts of the region， while it intensified in the western part. ③ Areas prone to soil water erosion in the eastern region of the agro-pastoral ecotone were mainly distributed in Chifeng City in the central part， and Zhangjiakou City and Xilinhot in the southwestern part of the study area. ④ The main contributing factor to dynamic changes in soil water erosion in the eastern region of the agro-pastoral ecotone from 2000 to 2023 was the vegetation cover management factor， with an average contribution rate of 64.18%. The combined effects of three factors （vegetation cover management factor， soil and water conservation measure factor， and rainfall erosivity factor） accounted for 23.12%. The average contribution rates of soil and water conservation measure factor and the rainfall erosivity factor were 10.57% and 2.13%， respectively. There were strong interactions among parameters of the RUSLE model， and the combined effects of multiple factors contributed significantly to the dynamic changes in water erosion in the study area. [Conclusion] From 2000 to 2023， soil water erosion in the eastern region of the agro-pastoral ecotone in northern China was generally stable. During the study period， with the increase in vegetation cover and the effective implementation of soil and water conservation measures， the aggravating effect of increased rainfall erosivity on water erosion intensity was alleviated to a certain extent. However， the soil water erosion situation in this region remains relatively severe. Areas with low vegetation cover and those without soil and water conservation measures are the key focus areas for soil erosion control in this region.