The invention discloses a heating furnace heat load distribution method and device and belongs to the technical field of industrial furnace engineering thermodynamics and heat transfer theory. A heating furnace sequentially comprises a preheating segment, a first heating segment, a second heating segment and a uniform heating segment. The method includes: optimizing a heat load theoretical distribution ratio of the segments of the heating furnace to obtain theoretical gas flow and combustion-supporting air flow, corresponding to the optimized heat load theoretical distribution ratio, of each segment of the heating furnace, and distributing gas flow and combustion-supporting air flow for each segment of the heating furnace. The device comprises an optimization module for optimizing theoretical distribution ratio of the heat loads of the segments of the heating furnace, a theoretical gas flow and combustion-supporting air flow conversion module, and a gas flow and combustion-supporting air flow distribution module. The heating furnace heat load distribution method and device has the advantages that gas consumption of the heating furnace is reduced, temperature control is more effective for the heating furnace, and billet heating quality can better meet the steel rolling requirements.