[Objective]This study aims to investigate the extent and underlying causes of terrace erosion in different regions of Ningxia triggered by an extreme rainstorm event, thereby providing a scientific basis for optimizing terrace design and soil and water conservation practices.[Methods]Based on the spatial heterogeneity of precipitation, a sampling transect was established along the rainstorm belt from southern to northern Ningxia. Focusing on nine small watersheds affected by the widespread extreme rainstorm event in Ningxia in 2024, we analyzed the spatial distribution patterns of different terrace erosion types (such as gully erosion and embankment collapse) through remote sensing interpretation, field measurements, and site surveys. The erosion volume was quantitatively assessed, and the driving factors (including rainfall intensity, terrace-ridge gradient, ridge integrity, and topographic factors) were explored.[Results]Within the study area, the primary terrace erosion types were identified as rill erosion, collapse, and gully erosion. Terrace erosion was predominantly concentrated in the lower 30% of the entire slope terrace sequences. Erosion volume varied significantly among different terrace types due to differences in design standards and maintenance quality, with older and slope-style terraces experiencing more severe erosion. The intensity of terrace erosion exhibited distinct regional variations across the watersheds. The Zhaoming watershed in Jingyuan County recorded the highest erosion intensity (7.08 × 103 t·km?2), while the lowest was observed in Tongxin County (41.41 t·km?2). Conversely, the Shujinggou watershed in Tongxin County demonstrated the highest soil conservation capacity (3.48 × 10? t·km?2).[Conclusion]Terrace erosion results from the combined effects of topography, hydrology, and engineering practices. The spatial variation in erosion intensity and soil conservation capacity is directly driven by natural factors and indirectly modulated by engineering measures (such as terrace-ridge gradient and ridge maintenance). Standardized ridge engineering, combined with vegetative buffer strips, can enhance terrace resistance to erosion. These findings provide a quantitative basis for early warning of terrace damage risks and the precise allocation of soil and water conservation engineering measures.