Abstract: Landslide-debris flow usually triggered by heavy rainfall is a kind of great hazard chain. This paper takes the landslide-debris flow which is located at the southern Dagou Village of Mapaoquan Town, Tianshui City, Gansu Province as an example. In order to get the physical parameters needed in the simulation, 4 groups of mudstone samples were taken from the lateral sliding surface of landslide area to conduct consolidated undrained(CU)triaxial tests and some conventional laboratory tests. The above experiments show that the friction angle of saturated mudstone is 11nd is smaller than that of channel slope. Based on the experimental results, we utilized LS-RAPID which is a simulation software system to simulate the movement process of the landslide-debris flow. The simulation results show that the landslide sliding average speed is 5.2ms-1 when it moved to toe of slope. The landslide was converted into debris flow under the powerful impact in the sliding process of landslide, then caused larger disaster area. Accumulation range and shape of simulation and actual measurement are the similar.