In the course of movement,the rock interaction with the debris flow can cause great damage to the buildings、bridges and other infrastructure. Fluid-solid Coupling Analysis will be new method to study the rock in the debris flow. The channel and sand dam system and GMO stone collision model will be established by Flow-3D, the characteristics of rolling boulders will be studied at RNG k~ epsilon turbulence model under three dimensional. Research shows that:The rolling velocity of the rock are positive corrilation with the velocity of the fluid,but the velocity of the rock is slower than the fluid; The angular velocity of the rock shows a a regular change in a certain range , this change is related to the shape of boulders. the movement of the boulder has a certain randomness and its speed is not related to the velocity and density of the fluid when it encountered a scarp, Kinetic energy attenuation range is 80.7%-98.8% in the gravel soil. The results provide reference for the impact study of the boulders and the design of debris flow control facilities.