Abstract: Construction of resistive structures can effectively reduce the deposit area of landslides and weaken the intensity of hazard. In this study, the landslide-debris flow is examined by using the 3D discrete element method, whose parameters are calibrated by comparing the results of the model tests and those of the numerical simulations. The influence of different slope gradients and the height of barrier on the impact force and the maximum of the horizontal running distance are further studied. The results indicate that for the three experiments with different slope gradients there are obvious differences in the impact force variation processes. When the slope gradient is 35° or 45°, the magnitude of the landslide-debris flow impact force undergoes two significant stages: linear increase and linear decrease. When the gradient is 55°, there are three stages of change in the time-history curve: linear increase, constant force stage and linear decrease. The higher the height of barrier is, the shorter the time duration of the constant force stage, and the longer the linear decrease stage is. Small particles (2.5~10 mm) have significant impact effects on the barrier. With the increasing height of barrier, the impact effect of the medium particles (10~25 mm) on the barrier gradually increases. The impact effect of large particles (25~60 mm) on the barrier has an abrupt change. Compared with other two kinds of particles, this impact effect is not significant during the whole motion. The running distance of the landslide-debris flow gradually decreases with the increasing height of barrier. Comparison of the resistance effects of the barrier under three slope gradients shows that the resistance effect is significant when the slope gradient α≤45°.