Most often used buffers for vertical lifting device is set in ground, is impacted by heavy down from top. A buffer was researched which was used in vertical fall protection device. When the vertical lifting device fell because of the rope broken, the fall protection device was triggered to stop it in mid-air. In this process, the buffer’s roles were to stop action and energy conversion. Its characteristics are: the fall protection device with a hydraulic buffer is mounted on a moving object (such as a elevator car); the moving object compresses buffer from the bottom to top; once the rope is broken, the vertical lifting device is immediately stopped, with a small initial velocity and ideal cushioning effect.