Abstract: The new smart underwater vehicle which runs near free-surface of the water is subject to wave disturbance and its rudder moment is complex. To simulate the water environment, a hardware-in-the-loop simulation (HILS) system was designed using methods of modeling, simulating decoupling design and automatic switching environment conditions. The real-time computation ability test of the simulation computer was implemented. The HILS and wave disturbance tests of the underwater vehicle were done. Test results show that the designed HILS system could meet the demands of the attitude control system HILS of the underwater vehicles. The approach presented in this research might be very useful to the design of the attitude control system and the undergoing shipping test of the underwater vehicles.