The invention relates to a device for automatically and repeatedly adding water through steam and a screw pump. The device is characterized in that an automatic water adding mechanism is additionally arranged on a pot for boiling rice dumplings, and when the rice dumplings are boiled, normal-temperature water can be automatically added into boiled water inside the pot. An impeller and an impeller shaft of the mechanism are longitudinally connected, the impeller shaft penetrates through a water storage basin to be connected with a bevel gear pair, the bevel gear pair is connected with the screw pump transversely arranged at the bottom of a water container, and when steam inside the pot is rapidly ejected through a steam ejection pipe, the steam inside the pot impacts the impeller, and the impeller drives the impeller shaft and the screw pump to rotate. When the screw pump rotates, the water is constantly sucked through the opening of a water inlet pipe of the screw pump and discharged into the water storage basin through the opening of a water discharging pipe of the screw pump. The water inside the water storage basin flows into the pot through a spiral throttling pipe; boiling is stopped inside the pot, and the screw pump stops discharging the water; and then, the device for automatically and repeatedly adding the water repeats the operation process in the automatic water adding stage. The device can automatically and repeatedly add the water into the pot in an unpowered manner, and therefore the outer layers of the rice dumplings will not fracture while being overdone.