Abstract: The dynamics of a single high-speed drip impacting with solidtarget are simulated by MSC.Dytran. The relations between the damage depthor damage width and the initial pressure, the velocity, the angle incidence ofdrips, the thickness of target are shown by curves, and the physicalmechanism is explained. Hopkinson spallation is explained by using thetheory of stress waves. The mechanism of water jet impacting rock is also discussedin this paper.