Abstract: Aiming at the character that the sliding mass acquire a high velocity in the set out-range, it shows that the landslide starting at a high speed is due to the sudden cut of the locking section to produce vibration, so that the sliding body accelerated, under the coupling effect and the force of its own gravity, landslide suddenly set-off. Taking Yunnan touzhai large-scale high-speed landslide as example, according to the field survey results, using fracture mechanics theory to analysis the process of vibration locking section from cut to accelerate. Calculating the strain energy released during the process of shear failure, the magnitude of the earthquake induced by the corresponding magnitude is consistent with the magnitude of the induced earthquake. And it is concluded that the start speed of the landslide is 46.1ms-1.On the basis of this, the PFC2D software is used to simulate the flow of the solid particles. The results show that with the lock solid particle stiffness increases, the particle accumulation of strain energy under the shear stress is larger, which leads to the sliding body to get a larger starting speed.