The invention provides a ship gravity telescopic flow-guiding drainage valve box, comprising a valve box, a flow guiding device, a drainage pipe, an upper position limit block, a lower position limit block and a lower dripping flow-guiding plate. The valve box is welded and fixed at the end of the drainage pipe; the external edge of the valve box is fixedly connected at the given position on a ship deck; the flow-guiding device is arranged inside the valve box and at the front side of the water outlet of the drainage pipe; the flow guiding device is connected with the valve box by a hinge; the circumference of the lower dripping flow guiding plate is fixedly connected with the valve box and the ship deck respectively; the upper position limit block and the lower position limit block are fixedly connected on the upper end box wall and the lower end box wall inside the valve box respectively. The ship gravity telescopic flow-guiding drainage valve box solves the effect of water dredgingand draining outside the shipboard on corresponding operation of an interference area when the ship stops at a dock or anchors at an anchor position. The ship gravity telescopic flow-guiding drainagevalve box controls the injection distance of the water dredging and draining outside the shipboard within 2 meters, shortens the interference area, leads other operations to be carried out normally, shortens the dock occupying period, reduces the freight cost, and has the advantages of small occupying space, quick operation and high safety.