The utility model discloses a heat accumulating type water level device for a steam boiler. Boiler comprising a boiler box, the side wall of the boiler box is fixedly connected with a water storage tank; a sliding plug is connected to the inner wall of the water storage tank in a sealed and sliding mode. The sliding plug is elastically connected to the inner wall of the water storage tank througha spring; and the upper end of the boiler box is fixedly connected with an air outlet pipe communicating with the interior of the boiler box, a channel communicating with the air outlet pipe and the interior of the water storage tank is formed in the side wall of the boiler box, the upper end of the boiler box is fixedly connected with a protective cover, and an open groove is formed in the upperend of the protective cover. According to the utility model, when the evaporation capacity in the boiler box is greater than the steam consumption of a user; the pressure in the boiler box is increased, the sliding plug is pushed to push water into the square barrel from the water outlet pipe, steam entering the water storage tank can heat the water in the water storage tank, heat energy of the steam is reduced, then the pressure in the boiler can be reduced, and the evaporation capacity in the boiler and the steam consumption of a user are in a balanced state.