Abstract: In order to solve the problem of fouling organisms blocking water exchange for deep-water cage and thus caused great difficulty in net changing and cleaning, developing submarine net cleaning machine and improving its cleaning efficiency were the important supporting facilities and technology for deep-water cage culture.Through analysis of operation principle of high-pressure submarine net cleaning machine, the structure geometric parameters calculation expression of nozzle were deduced based on energy equation.Optimal pressure and flow in high pressure water generating system were selected, and aperture/slenderness ratio of nozzle was calculated.Hydraulic parameters were calculated.These parameters supplied theoretical support for optimizing the structure of net washing machine.