The invention discloses an outdated coal-fired heat boiler. Thermodynamic optimization design is adopted, a spiral heating pipe is adopted for a boiler body and matched with a plurality of flue heat exchange pipes, water is heated for the first time through the spiral heating pipe in the boiler body, heated for the second time through the flue heat exchange pipes and then enters a heat circulation pipe, full absorption of heat is achieved, and automatic adding of fuel is achieved; a closed-loop negative feedback control adjusting mechanism is formed between an automatic fuel feeding device and the boiler body temperature, the rotation speed of a motor is controlled through a single chip microcomputer according to the temperature, accordingly feeding of the fuel is controlled, and stable output of the heating temperature is achieved; the outdated coal-fired heat boiler is based on dispersed heating, elements of economy, environmentally protection, practicability and efficient energy conservation are comprehensively considered, and the outdated coal-fired heat boiler is particularly suitable for heating of rural areas and remote areas in winter.