Debris flow are a common geological disaster in mountainous areas. Researching the accumulation and energy characteristics of debris flow is of great importance for the defense planning of potential danger areas and advancing major engineering projects in disaster-prone regions. Currently, there is a lack of systematic study on the energy changes during the occurrence of debris flow disasters and the accumulation process after the failure of resistance structures. Based on the disaster-prone areas of Tibet, this study selects samples that match the real environment to conduct landslide experiment. At a macro level, it investigates the accumulation characteristics of debris flow after the destruction of retaining walls. It was found that the final slope angle of the slope body after the destruction of the wall did not reach the internal friction angle of the particles, and many particles within the slope body did not move. Additionally, a particle energy simulation was performed. At the mesoscopic level, the study examined the energy changes in debris flow particles, finding that as the slope angle increased, the energy consumption of the particles tended more towards friction energy dissipation rather than collision energy dissipation. In simulations of low slopes, the friction energy dissipation of multiple particles did not account for a small fraction like in single-particle simulations but maintained a significant proportion. In terms of three-dimensional simulation, a method to create real three-dimensional topographic maps was proposed, and the debris flow disaster process was divided into three stages, with detailed explanations given for the energy changes in each stage. The study provides a comprehensive interpretation by correlating the macroscopic flowing characteristics of debris flow with the microscopic energy changes.