Abstract: Check dam is an important project commonly used in the prevention and control of landslide disasters. It has the functions of raising the base of erosion, retaining silt, and stabilizing the channel. In the current research on debris flow control, simple geometry is often used to replace the actual shape of a check dam and gullies, and there is a lack of detailed research on the flow field around a reality check dam. To optimize the check dam design, improve the erosion resistance of debris flow, and extend the service life of check, this paper explores a three-dimensional multi-physics coupling model for RANS k- turbulence of a dilute debris flow under continuous-phase Euler coordinates to investigate the flow field distribution, turbulent kinetic energy, and impact load change of dilute debris flow around check dam in the event of a three-year rainfall event. The results show that:the downstream surface of check dam can effectively reduce the turbulent flow before the dam. Check dam has different types of backflow vortex at the crest and back surface. There are high-energy side cut and undercut turbulence at the back surface of check dam, in the back of check dam. Protective measures should be taken on both sides of the abutment and the bottom of the check dam. The research results can provide a reference for the design of check dam and prevention of debris flow.