Disclosed is a method for controlling brittle inclusions in cord steel. The method includes the following steps: adding alloys at the moment of tapping in a furnace primary smelting stage and adding silicon carbide and synthetic slag to a top of ladle slag at the end of tapping to form slag; adding the alloys in a refining stage and feeding carbon wires; and adding lime, silicon carbide, the synthetic slag, and performing electrification to slag, where the slag composition meets the following conditions: CaO/SiO2=0.9-1.2, Al2O3≤5%, MgO 4-8%, [MnO+T.Fe] 2-5%.