Abstract: 【Objective】 Against the backdrop of global climate change and frequent extreme rainfall events, achieving precise monitoring and mechanistic understanding of soil erosion is essential for ensuring ecological security. This study integrates 3D laser scanning technology and geomorphological information entropy theory to establish a technical framework for quantifying the spatiotemporal characteristics of soil erosion and elucidating its driving mechanisms. Methods Indoor simulated rainfall experiments were conducted using a generalized physical model of the Qiaogou small watershed in the loess hilly-gully region. Six experimental scenarios were designed with varying rainfall intensities (30, 60, and 120 mm/h) and check dam configurations (no dam, single dam, double dam). High-resolution topographic point cloud data before and after erosion were acquired using a 3D laser scanner. Digital Elevation Models (DEMs) were generated, and combined with geomorphological information entropy theory, to systematically analyze the spatial distribution of erosion–deposition, intensity changes, and their responses to rainfall and soil conservation measures. Results The results indicate that erosion primarily occurred on slopes and gullies, while deposition was concentrated in gentle slope sections or low-lying areas of gullies. Check dams effectively intercepted sediment and regulated runoff, significantly reducing erosion under low and medium rainfall intensities, though their effectiveness diminished under high-intensity storm conditions. The growth rate of geomorphological information entropy was positively correlated with topographic relief, with the steepest areas showing the most significant entropy increase (up to 14.34%), confirming its utility as an effective indicator of erosion intensity. Conclusion This study demonstrates the strong potential of combining 3D laser scanning technology and geomorphological information entropy theory for accurately quantifying soil erosion processes, evaluating the effectiveness of soil and water conservation measures, and revealing underlying erosion mechanisms. It provides a robust technical and theoretical foundation for soil erosion research and control.