The invention discloses a manufacturing method of a fire grate section and belongs to the technical field of manufacturing. The manufacturing method of the fire grate section comprises the following steps that n' grate section bodies are combined; the grate section bodies are coated with a material layer of the same material as a second welding wire; the grate section bodies are placed onto base plates, and connection sections of the adjacent grate section bodies correspond to two opposite fluid grooves of the adjacent base plates; procedure code preparation is conducted; welding preparation is conducted; surfacing of a first supporting structure is started; surfacing of the first supporting structure is stopped; surfacing of a second supporting structure is started; surfacing of the second supporting structure is stopped; a first welding wire in an automatic wire feeder is replaced with the second welding wire; surfacing of a formed part is started; the base plates are detached and transferred to a heating furnace; the heating temperature of the heating furnace is set; a heating part of the heating furnace is started to thoroughly smelt the first supporting structure and the second supporting structure, and the base plates are separated from the fire grate section; and the heating furnace is closed, and the fire grate section is taken down after the part is cooled. The fire grate section manufactured by the manufacturing method is high in strength, simpleness and reliability are achieved, and the labor intensity is low.