The study designs a passive anti-roll tank,sets damping plates at both ends of the rectangular tank to improve the stability of the hull.The anti-roll capacity of the tank is evaluated by simulation.The simulation results can clearly show the state of the water tank when the ship is shaken.The analysis shows that the system can effectively reduce the amplitude of hull rocking,improve the safety and stability of the ship at sea,so as to provide reference for future marine engineering application.