Nozzle spacing is an important factor influencing the effect of high-pressure water jet cleaning. When the nozzle incidence angle, the deflection angle and the target distance are determined, the size of the nozzle spacing determines the overlap of the water jet, the overlap is too large or too small will reduce the cleaning effect. In this paper ,using CFD software to simulate the flow field inside and outside of the high-pressure water jet nozzle, analysis the jet axial velocity, pressure distribution, and discussed this changes in the case of different spacing between the nozzles when the nozzle structure are same, and choose an reasonable spacing to ensure the cleaning effect.