The long tube fillet joints of boiler header are complex and numerous. the adoption of automation welding for the structure is extremely difficult because of little space and bad welding performance. Based on the characteristic of the structure,mechanized automatic welding has been chosen as its primary technical direction of automation implementation,so the mechanical welding welding work process and the corresponding mechanical welding equipment has been designed and developed. Because of the characteristic of wire feeding difficulty for the flux-cored wire,the wire feeding tube,contact nozzle and welding power source have been mainly considered and the equipment wire feeding function has been improved and verified,so the stability of the equipment have been guaranteed and it has been successfully applied in production practice.