The invention relates to a heating-furnace cogeneration system and a method thereof, and belongs to the field of waste energy and heat recovery. The cogeneration system comprises a heating furnace, a heating-furnace waste heat boiler, a heating-furnace air preheater, a heating-furnace heat-pipe coal gas preheater, a heating-furnace tail suction fan, a superheated steam boiler, a turbogenerator set and a chemical water system, wherein the heating-furnace tail is orderly provided with the heating-furnace waste heat boiler, the heating-furnace air preheater, the heating-furnace heat-pipe coal gas preheater and the heating-furnace tail suction fan along the fume flow direction, and used for recovering the fume waste heat of the heating furnace; the heating-furnace waste heat boiler is used for generating electricity; and the chemical water system is used for providing supplementary water for the heating-furnace waste heat boiler and the superheated steam boiler. The invention enables the superheated steam boiler to still ensure the low-load stable operation of the cogeneration system when heating furnace is to be rolled, increases the steam parameter of the heating-furnace waste heat generating equipment by utilizing the superheated steam boiler, and enhances the generating efficiency. The invention maximally recovers the waste heat of the heating furnace, thereby having favorable economic and environmental benefits and high values for application and popularization.