Urbanization and infrastructure projects generate huge amount of construction and demolition waste (CDW), posing significant challenges for the environment and human health. In order to reduce the environment and safety risks caused by the CDW landfills, this study was amid to utilize plant roots to develop a root-CDW-soil system for strengthening the CDW and enhancing the slope stability of CDW landfills. A series of experimental analyses were conducted, focusing on shear tests of root-soil composites under various moisture conditions and root content ratios. The results indicate that the inclusion of ryegrass roots plays a critical role in significantly enhancing the shear strength of the soil, and the soil samples reinforced with 0.6 g of ryegrass roots exhibited a shear strength increase of up to 35% compared to the unreinforced samples. The slope stability treated by the plant roots was evaluated by finite element simulations under different rainfall conditions. The factor of safety (FoS) for reinforced slopes increased from 1.18 to 1.59 after five days of heavy rainfall (480 mm/d), highlighting the significant improvement in stability provided by the root systems. These findings suggest that the root-soil system offers a sustainable solution for slope management, reducing risks associated with construction waste and extreme weather conditions.Implications: Urbanization and infrastructure projects generate significant waste, posing environmental and safety challenges. This study investigates the enhancement of slope stability through the integration of ryegrass root systems. The findings indicate that ryegrass roots substantially improve soil shear strength and overall slope stability. Furthermore, the study demonstrates that these root systems enhance resilience to heavy rainfall, thereby mitigating the risk of slope failure. These results suggest that plant root systems offer a sustainable solution for slope management, effectively addressing environmental concerns related to construction waste and extreme weather conditions. This research provides a comprehensive understanding of the physical and mechanical properties of root-soil composites, thereby promoting their practical application in slope stabilization.