Flux-cored wire gas shielded welding is a high quality and efficient welding method,which is widely applied to the pressurebearing welds on the header made of carbon steel,SA-335 P12 and 12 Cr1 Mo VG in boiler industry in the beginning of 21 st century. And the nationalization of these flux-cored wires has been realized. However,for SA-335 P91 material,because the development of flux-cored wire is difficult,the requirements of procedure performance and mechanical property can not be met simultaneously,and R&D cost is high,only a few foreign renowned welding material suppliers research and develop the formula of the flux-cored wire and there are no corresponding welding materials in China now. Therefore,the flux-cored wires for SA-335 P91 made by several famous welding material suppliers are tested,compared and analyzed to study the influence of welding parameters and heat treatment parameters on the properties of SA-335 P91 flux-cored wire joint,thus the influence rules are analyzed and the most reasonable range of welding and heat treatment parameters is obtained. Besides,the macrostructure and microstructure of the welds are observed and analyzed,and further recommendations for improvement are put forward.