In order to achieve the safety and environmental protection of the tank cleaning, the cavitation water jet cleaning technology is introduced into the tank cleaning work.A central body nozzle with a diffusion angle is studied.The Fluent calculation software is used to simulate the cavitation jet induced by the central body nozzles with different diffusion angles,and the pressure, axial velocity and cavitation volume fraction are analyzed.The simulation results show that the effect of cavitation induced by the central body nozzle containing the diffusion angle under the pressure inlet of 15 Mpa is significantly better than that of the central body nozzle without the diffusion angle.At the same time, the central body nozzle has different effects due to its different diffusion angles.When the diffusion angle is 15°, the effect of cavitation induced by the central body nozzle is the best.Therefore, a reasonable selection of the structural parameters of the central body nozzle can better improve the quality of the tank cleaning.