The utility model discloses a novel no-pressure boiler which is mainly composed of a boiler core, a boiler container, a boiler cover and a shell, wherein the boiler core is also composed of a combustion chamber, a flue and a chimney, wherein the combustion chamber forms a tower shape and adopts the inverse combusting mode of a single grate. The boiler container is provided with double layers, and the outer container is covered outside the inner container; a water tank is arranged between the inner container and the chimney, and a ball float valve is arranged in the inner container. Because the utility model adopts the structure, the utility model is suitable for various coal kinds; the environment pollution is small; the thermal efficiency is high; water can continuously fills; boiling water can be continuously supplied; the utility model can not be operated by a special person; the utility model can realize the requirements of multiple purposes of heating, showering and water drinking.