Aiming at the problem of swing of the payload in case of the ship operation at sea, a new mechanical antiswing device is put forward. A stable force triangle was formed by using antiswing rope in the antiswing ring, and the pendulum of the payload was effectively reduced. Through these methods, the swing of the payload were restrained. The principle of the antiswing device was described, and the hydraulic system was designed according to action requirements of crane and antiswing device. Using AMESim software, the response of the motor in case of the ship rolling 4° was simulated with analysis. The results show that the response of the hydraulic motor is good, and the rationality of the hydraulic system is verified. Set up the test platform and analyzed the response of the motor, the response of the motor is timely, and the feasibility of the hydraulic system is verified.