The utility model relates to a slag skimming device for melting metal, which comprises a plate which is connected with a slag-raking machine, wherein two supporting rib plates which are mutually parallel and are obliquely extended forwards are arranged on the surface of the plate opposite to the slag-raking machine, and a hetero-type rake head is arranged on the lower end of the support rib plate. The appearance of the rake head is the same as or is approximating to the inner wall shape of a molten iron tank. The slag skimming device can effectively clean slag between the molten iron tank and the hetero-type rake head surface without resulfurization, which is made through welding high temperature resistance steel plates, and has simple structure and lower manufacture cost.