Structural planes are commonly found in the slopes of the Loess Plateau. Combined with disturbances from human engineering activities, their growth is further accelerated, leading to frequent geological disasters in the region. In this study, a large-scale physical model test was conducted on loess slopes with structural planes engineering excavation, at a landslide in the southern Jingyang Tableland as a prototype. The key findings are as follows: (1) By examining the response process of deformation and the stress field, this study analyzes the deformation propagation mechanism of the structural plane and the associated instability mechanism. (2) The deformation field and plastic zone of the slope are primarily concentrated beneath the pressure plate, gradually extending towards the toe of the slope along the structural plane as excavation progresses. Excavation induces stress redistribution, which exacerbates slope deformation and failure. (3) Although the final loading conditions differ only slightly, post-excavation behavior varies significantly. This suggests that higher loading levels approach the soil's yield threshold, leading to nonlinear plastic deformation and exacerbating the impact of excavation on slope stability. (4) Structural plane is the primary regions for landslide occurrences. At the critical point of slope failure, the stress curve rapidly declines within a short period, while the displacement curve correspondingly increases. (5) Future research can integrate multi-scale experimental approaches and multifactor coupling effects while enhancing long-term monitoring to improve the reliability of engineering applications.