Abstract: The study of rock avalanche deposits can reveal the changes in rock avalanche energy. Based on the survey of the collapse site in Pusa village, this paper combines the digital surface model (DSM) of the collapsible sedimentary body with the statistical analysis of the particle size of the collapsed rock avalanche to carry out a preliminary analysis of the rock avalanche movement process. By using the Scheidegger formula to estimate the velocity of the rock avalanche, we can draw the following conclusions. (1) Calculation the particle size of the blocks on the surface of 13 consecutive rectangular zones (A1~A13) along the main slip direction gets the rules as follows: the farther away from the collapse source area, the smaller the content of small particles, and the smaller the content of large particles. (2) The sediment particle size is related to the movement kinetic energy of rock avalanche. The greater the velocity, the greater its ability to carry rock masses. On the contrary, the rock mass content is less. (3) According to the different characteristics of the deposits, the accumulation area is divided into initial accumulation area, concentrated accumulation area, stable accumulation area and accumulation weakening area.