The invention relates to a novel energy-saving boiler which has the advantages of high combustion efficiency, fast temperature rise, low smoke discharging temperature, favorable whole operation effect and convenient for overhauling, heat absorption area can be effectively increased, and exhaust gas can be flown smoothly. The novel energy-saving boiler comprises a furnace cavity, a furnace pipe isarranged on the upper part of the furnace cavity, a smoke tube is arranged in the furnace pipe, the furnace pipe is filled with liquid, a hot-water outlet is arranged on top of the furnace pipe, a cold water tank is arranged at one side of the furnace cavity, a round platform-typed horn opening is arranged in the furnace cavity, a sealed water circulation system is formed in the round platform-typed cavity between an outer round platform and an inner round platform, an evaporator is arranged at one side of the round platform-typed horn opening, an opening on an upper bottom surface of the round platform-typed horn opening is directed at the evaporator, and a lower bottom surface of the round platform-typed horn opening is directed at a front arch. The furnace pipe is connected with an exhaust gas heat recovery device, and the exhaust gas heat recovery device is connected with a three-connecting-tower desulphurization dust remover.