Abstract: Although rainfall is abundant during the rainy season in rocky desertification areas, the complex karst geological structure results in leakage, leading to soil and water shortage on the slopes, which restricts the vegetation restoration of rocky desertification slopes. How to achieve the collection and utilization of rainfall has become a hot issue in the vegetation restoration of rocky desertification slopes in green highway construction. At a rocky desertification slope section of the Heba Expressway in Guangxi, the vegetation restoration technology of a new type of stepped slope slab was applied, and the indoor experiment and engineering numerical simulation analysis of rainfall collection and utilization of the vegetation slab were carried out based on this technology. The results show that, due to the lack of simulation of slope surface runoff inflow into the slabs, the influence of plants on the water storage process of the slabs is mainly reflected in the interception of rainfall by the plant canopy. During the dry period after rainfall, the soil in the slabs can maintain a suitable moisture content for plant growth for a period of time. Through the engineering numerical simulation analysis, the rainfall collection and water-holding capacity of the vegetation slabs under different rainfall characteristics were explored, which helps to reveal the spatial distribution characteristics of rainwater collection in the water storage layer at the bottom of the rocky desertification slope slabs and the moisture content in the upper soil layer during the rainy and dry seasons, and identify potential problems in the engineering implementation and propose countermeasures. The research results can provide a theoretical basis for the on-site application of vegetation slabs on rocky desertification slopes, and promote the development of green highway construction in rocky desertification areas.