Numerical simulation of a vertical round jet in wave-current environment was performed using the Large Eddy Simulation (LES) method. The zero-gradient condition combined with a sponger layer was imposed at the outflow boundary to reduce the numerical reflection. The linear and non-linear superposition of wave and current boundary conditions were adopted at the inflow boundary respectively. The latter was proved to be of higher precision by comparison of the velocity profiles with the experimental data. Numerical results show that under the combined effect of wave and current, an apparent "water masses" phenomenon appears on the upper part of jet body and the jet velocity vectors are deflected closer to the bottom than that in a pure current environment, which is consistent with the previous experimental observations.