The motion and diffusion behaviours of multiple jets in wave-current environment were studied by using a 3D large eddy simulation model, and the diffusion and dilution mechanism of jets in wave-current environment was discussed. Then, the influence of hole spacing on the interaction between two-hole jets and environmental water was analyzed and the optimal relative hole spacing was given. The simulation results showed that, due to the strong interaction between cross-flow and wave, the three-dimensional vortices in the flow field at the wave trough phase are rich in structure, large in scale and numerous in number, which is conducive to the mixing between jets and environmental water, and between jet and jet. Hence, the multiple jets in wave-current environment have a better dilution than that in current only environment. With the increasing of hole spacing of dual jets, the interaction between the two jets becomes weaker while the interaction between jets and environment water becomes stronger. The best dilution effect of two-hole jets is obtained when the hole spacing is 7.0 times of the jet diameter.