The invention relates to a bottle cap opening and closing device for a sampling bottle of an unmanned ship. The bottle cap opening and closing device for the sampling bottle of the unmanned ship comprises a force difference device and a manipulator; the force difference device is relatively fixed on a deck bracket of the unmanned ship, and the manipulator is connected with the force difference device, and can slide up and down relative to the force difference device. The main function of the bottle cap opening and closing device for the sampling bottle of the unmanned ship is to achieve the purpose of opening and closing a stopper of the sampling bottle of the unmanned ship to automatically collect water samples. The bottle cap opening and closing device adopts the one-dimensional motion manipulator, to mainly move up and down and grab. When the sampling bottle is placed in shallow seawater, the manipulator grabs the stopper and opens the sampling bottle. The water samples are quantitatively collected by controlling the opening time of the stopper. When the time is over, the manipulator plugs the stopper back to a bottle mouth again to collect the water samples. The bottle cap opening and closing device for the sampling bottle of the unmanned ship disclosed by the invention has the characteristics of agility, compactness and light weight, and excellent control precision and path precision, thereby being an ideal choice for material handling and assembly application, and further is relatively simple in electric control and has high full-automation.