Rubble deposits with a high concentration of rock debris were created after the powerful earthquakes in Jiuzhaigou. Because of the restricted soil resources, water leaks, and nutrient deficits, these deposits pose serious obstacles for vegetation regeneration. The purpose of this study was to investigate the main mechanisms controlling soil water retention and evaluate the effects of different amendments on the hydraulic characteristics and water-holding capacity of collapsed rubble soils. Fine-grained soil, forest humus, crushed straw, and organic components that retain water were added to the altered soils to study the pore structure images and soil-water characteristic curves. Comparing understory humus to other supplements, the results showed a considerable increase in the soil's saturated and wilting water content. The saturated water content and wilting water content rose by 17.9% and 4.3%, respectively, when the percentage of understory soil reached 30%. Additionally, the enhanced soil's microporosity and total pore volume increased by 45.33% and 11.27%, respectively, according to nuclear magnetic imaging. It was shown that while clay particles and organic matter improved the soil's ability to adsorb water, they also increased the soil's total capacity to store water. Fine particulate matter did this by decreasing macropores and increasing capillary pores. These results offer an essential starting point for creating strategies for soil repair that would encourage the restoration of plants on slopes that have been damaged.