The shape is round or irregular, and it is made of thin steel strips. A certain composition of powder is filled in it, and then drawn into a seam flux-cored welding wire. Or the seamless flux-cored welding wire made by filling a large amount of powder in the steel pipe. The deposition efficiency of welding with this kind of fluxed wire is higher. Because of the good adaptability to steel and the trial production cycle is shorter than that of other welding wires, the utilization rate, amount and scope of use of the welding wire are constantly expanding.