Abstract: The secondary oxidation caused by compositions of refining slag and Ca treatment on oxide inclusion was studied in TP347H stainless steel by EF+VOD+IC process. In industrial trials, the aluminum is used as the final deoxidation during VOD process. The FeO and SiO₂ contents in refining are decreased and the quaternary basicity is higher than 1.3. Then the total oxygen content is below 0.003%. With Ca-Si wire feeding and soft blowing the hard Al₂O₃ and MgAl₂O₄ inclusions are transformed to CaO-Al₂O₃ inclusion. The amount of MgAl₂O₄ inclusion is reduced and the melting point of inclusion is below 1500℃. This kind of inclu-sion is liquid during steelmaking process and it is easy to coalescence and flotation. And in the following rolling and forging process the inclusions have a little deforming ability with the matrix deformed and prevent the ingot crack.