During the high-speed and long-runout sliding failure process of large landslides, severe friction and heat generation in the sliding zone induce an interface friction effect between the debris flow and the bedrock, influencing the final accumulation morphology of the landslide. In this paper, a two-dimensional landslide model of the Yangbaodi landslide in Shenzhen was established using the material point method. A contact algorithm was introduced through a multi-background grid method to conduct numerical simulations on the initiation, sliding, and accumulation processes of the landslide. The results show that after initiation, the landslide moves over a long distance in a flow-like state along the bedrock. Influenced by the topographic and geomorphic characteristics of the bedrock, local accumulation is formed in some gently inclined areas. The final accumulation morphology is relatively close to the calculation results of methods such as the particle finite element method, which preliminarily verifies the effectiveness of the method in this paper. Calculations changing the friction coefficient between the debris flow and the bedrock reveal that the interface friction effect significantly influences the movement behavior of the debris flow. The maximum sliding velocity and farthest sliding distance decrease as the friction coefficient increases. However, the soil deformation of the debris flow near the bedrock area is more obviously affected by friction, and the equivalent plastic strain conversely increases as the friction coefficient increases. At the same time, a large number of discontinuous plastic deformation protrusions are formed, influencing the final accumulation morphology of the debris flow. The research results can provide an effective technical means for analyzing the failure mechanism of natural landslides under the interface friction effect.