The origin of calcium treatment of molten steel in ladle and adding calcium method as well as developed gas rotary feeding wire lance and high-density cored-wire with elliptic section are presented in this article. It is suggested that using the experience of welded pipe forming machine the technical revamp of cored-wire machine shall be carried out at cored-wire forming enterprises and machine manufacture enterprises to produce elliptic cored-wire forming machine and change the cylinder face gear for feeding wire to the arc tough gear for feeding wire； and at steel works the stroke of mobile guide tube in feeding process should be increased to achieve the feeding wire calcium treatment in molten steel.