The invention provides a low-voltage electrode boiler, and belongs to the field of boiler equipment manufacturing. The low-voltage electrode boiler comprises an electrode bar, a boiler body, a floating water tank and an inner container, wherein the inner container is fixed in the boiler body, and the electrode bar is provided with an electrode; the electrode is fixed to the top of the inner container and inserted into the inner container; a vertical water inlet pipe is mounted at the bottom of the inner container; the floating water tank is located in the inner container, arranged on the waterinlet pipe in a sleeving mode and can slide up and down in the length direction of the water inlet pipe; and an opening is formed in the top of the floating water tank, an elbow is arranged at the top of the water inlet pipe, and the elbow faces the opening. According to the low-voltage electrode boiler, the floating water tank is arranged in the inner container, so that the water level in the inner container of the electrode boiler can be raised, the amount of water heated by electrodes in the inner container is reduced, the air outlet speed is increased, the starting speed is increased, andpollution discharge and cleaning in the boiler are facilitated.