The invention relates to a quick-closing valve for a ship. The quick-closing valve comprises a valve body, a valve rod and a valve cover. The valve cover is connected and fixed with the valve body, the valve rod is arranged in the valve cover and can move up and down relative to the valve cover, a hand wheel is arranged at the upper end of the valve rod, a valve disc is arranged at the lower end of the valve rod and extends into the valve body to be in sealed connection with the sealing surface of the valve body, a thread is arranged on the upper portion of the valve rod, the lower portion of the valve rod is sleeved with a spring, and the spring is arranged between the valve disc and the valve cover. A sliding cavity is arranged in the valve cover, a hexagon nut is arranged in the sliding cavity and connected with the valve cover through a locking mechanism, and the valve rod moves up and down through the hexagon nut. After the locking mechanism is unlocked, the hexagon nut rapidly slides under the spring force effect to achieve sealing of the valve disc and the valve body. The rapid locking mechanism is formed by a cylinder, a connecting rod, a locating pin and the hexagon nut; and the valve is quickly closed through the locking mechanism and the spring. The quick-closing valve is convenient to control and can be quickly closed in case of emergencies, time for rushing to deal with an emergency is saved, and loss expansion is avoided.