Method for molten steel refining by corundum slag

The invention provides a method for molten steel refining by corundum slag. The method comprises the following steps: after steel tapping from a converter, adding 1-2 Kg/(ton of steel) of corundum slag into a steel ladle; after the steel ladle is subjected to the steel ladle refining procedure, adding 0.5-1 Kg/(ton of steel) of corundum slag into the steel ladle again, then heating with an electrode, adding fluorite and active lime into the steel ladle for slugging, adding active lime and aluminous deoxidizing agents in batches to carry out desulphurization refining; wherein the corundum slag is slag generated during vanadium iron alloy production by an electric thermite method, and the corundum slag comprises the following components by weight percent: 65-75% of Al2O3, 15-25% of CaO, and 5-10% of MgO. The method of the invention solves the recycle problem of slag generated in vanadium iron alloy smelting, and has good refining desulphurization effect.