The utility model provides a water vapor protective annealing device which comprises a cooling water tank and an annealing furnace, wherein a furnace tube is arranged in the annealing furnace. The water vapor protective annealing device is characterized in that the outlet end of the furnace tube is immersed in the water surface of the cooling water tank, an included angle between the outlet end of the furnace tube and the water surface of the cooling water tank is less than 45 degrees, the furnace tube produces a high temperature under the action of baking implemented by electric stove wires, water in the cooling water tank flows back to the inside of the high-temperature furnace tube, and the water rapidly meets the high temperature and produces water vapor in the process of entering the high-temperature furnace tube, so that the whole furnace tube becomes a water vapor pipe, and a copper wire is running in the water vapor pipe, thereby also achieving an expected annealing effect. The water vapor protective annealing device disclosed by the utility model is simple in structure and low in cost, has an energy saving effect, and can greatly reduce the processing cost.