The high- water jet technology has the superiority of the wide range of working medium and environmental protection, and can be used to break the submarine gas hydrate formations. In this paper, LS-DYNA finite element program is used to simulate the fragmentation process of submarine gas hydrate formations with high-pressure water jet under submerged condition. The effects of four key parameters (jet velocity, nozzle diameter, target distance and incident angle) on the erosion volume of hydrate formations are studied. The following conclusions are drawn: the fragmentation of hydrate sediments needs to meet the requirement that jet velocity is higher than the critical velocity; the erosion volume gradually increases with the increase of jet velocity; the increase of nozzle diameter will lead to the increase of the radial erosion volume of formations, thus increasing the overall erosion volume; the increase of target distance will increase the energy loss of water jet in the process of water movement, leading to the decrease of erosion volume; the erosion volume will increase first and then decrease with the increase of nozzle incidence angle, eventually tending to be stable. When the incident angle is 10°, the erosion volume can reach the maximum value.