As a new water jet technology, the cavitating jet has the characteristics of high energy density and strong impact force. It has a good application prospect in net cage cleaning devices. To explore the formation mechanism and erosion capability of cavitation jet and provide theoretical reference for its application in net cage cleaning devices, this paper designs a shear-type cavitation nozzle with reference to the working parameters of existing commercial cleaning robot, selecting pressure of 15 MPa and flow rate of 27 L / min. The inner flow and cavitation characteristics of the nozzle are studied through the Mixture multiphase flow model of FLUENT software. The erosion capability and working target distance of cavitating jet in the submerged environment were tested by flume experiment. The results show that the velocity at the nozzle outlet obtained by numerical simulation is very consistent with the velocity calculated by theory, and the difference is less than 0.5%. The cavitation bubble of the shear-type cavitation nozzle formed in the diffusion section of the nozzle and developed and collapsed in the jet. Because the impact force of cavitating jet is the result of the combined action of high-speed jet and cavitation bubble, the erosion capability of cavitating jet first increases and then decreases with the increase of target distance in submerged jet test, and the erosion performance of inclined jet impinging on the surface of the target is significantly higher than that of vertical jet impinging on the surface of the target. Compared with a high-pressure jet, the cavitating jet has a stronger impact force, so it is more suitable for net cage cleaning, but it has the best working target distance to make the erosion of the jet better.