Based on volume of fluid (VOF) technique, the flapping motion of submerged turbulent plane jet in shallow water impinging vertically onto the free water surface was reproduced.To study further on the flapping motion, the power spectrum density, the centerline velocity decay, as well as the mean velocity profiles of the jet were all investigated in this paper.The results are in great agreement with those of theoretical analyses, and the results show that the flapping motion is a new flow pattern of submerged turbulent plane jets.