Based on the propulsion requirements of a certain boat, taking the design conditions of the water jet propulsion as the analysis object, using the CFD method, the impact of engineering application factors such as the impeller tip clearance, the flow channel grid density, the water depth of the sailing area, and the lateral spacing of the double pumps on the propulsion performance is studied. Impact. The results show that a smaller tip clearance can better ensure the propulsion performance; too dense grid bars will increase the damping effect of the runner inlet and affect the flow channel's ability to supply the jet; the blocking effect is obvious when the water depth is too small in the sailing area , The thrust reduction ratio is relatively large; the distance between the two pump shafts has a small effect on the hydraulic performance and propulsion performance of the water jet. The above conclusions provide a reasonable basis for the design, construction, installation and use of water jets.