Abstract: To explore the influence of water depth on the drag reduction effect and the optimal drag reduction height of the interceptor. Based on the numerical solution approach of RANS equations, the flow field around a single high-speed ship with various height interceptors is numerically simulated. Firstly, the validity of the numerical method is verified by the DTMB5415 high-speed ship. Then, the flow field around a high-speed monohull ship is numerically simulated under different interceptor heights and water depths. Based on the numerical results, the resistance, navigation state, and flow field characteristics of different working conditions are analyzed. The results show that the drag reduction effect of the interceptor has an obvious shallow water effect; the optimal drag reduction height is unchanged with the change of water depth, and the reduction of the trim angle of the interceptor is unchanged with the change of water depth. The interceptor has a certain effect on reducing the wave-making behind the ship, but the effect decreases with the decrease of water depth. The research content has certain practical reference values for the application of the interceptor in shallow water.