[Objective] The variation of the erosion depth of debris flow solid mater, and the relationship between the corresponding scouring rate and different influencing factors were explored in order to provide reference for debris flow prediction and prevention engineering design.[Methods] According to the principle of the laser rangefinder, the variation of the erosion depth of debris flow solid matter over time and the relationship between the corresponding erosion rate and different influencing factors were explored, including the incoming flow, hydraulic radius, and gully bed longitudinal slope and the content of fine particles.[Results] The scour rate showed an exponential relationship with the hydraulic radius, a positive correlation with the incoming flow, and an exponential relationship with the energy slope gradient. If the solid matter was uniformly scoured, the scouring rate had a linear positive correlation with residual shear force. For the solid matter with a relatively low initial moisture content, the scouring rate increased slightly with the increase of the content of fine particles.[Conclusion] Under the condition of thin runoff, the energy slope gradient had a greater influence on the erosion rate, compared to the hydraulic radius.