The utility model discloses a device for moisturizing strip steel in an electroplating tank through a gravity method. The device comprises a circulating tank and four spraying pipes, wherein a water inlet pipe and a water outlet pipe are respectively arranged on the circulating tank; a booster pump and a corresponding control valve are additionally arranged on a pipeline of the water outlet pipe; the four spraying pipes are respectively located above a strip steel downlink positioning roller, a strip steel uplink drying roller, a strip steel uplink drying roller and a pressing roller of a conductive roller; a plurality of nozzles are arranged on the spraying pipes and are uniformly distributed in the width direction of the strip steel; and each spraying pipe is connected with outlet pipelines of the booster pump on the water outlet pipeline of the circulating tank through connecting pipes, and valves are arranged on the respective connecting pipes. When the device is adopted, surface moisturizing capacity of the strip steel discharged out of the electroplating tank can be effectively improved, uniformity of the surface moisturization of the strip steel can be guaranteed, and zinc sulfate remained on the surface of the strip steel can be obviously reduced, therefore, the defects of electroplating spots due to the gravitational electroplating process is reduced, the surface quality of the strip steel is obviously improved, and the stable operation of a unit is guaranteed.