Abstract: The research progress of oxides in the high performance steels by additive manufacturing was reviewed in this paper, including the characteristics and formation of oxides, the influence of oxides on the molten pool, the mechanism of oxide destruction and reconstruction, and the movement of oxides in the molten pool. In addition, the design idea for the oxide harmlessness was also described to provide the reference for the research of the oxide harmlessness during the metal additive manufacturing process in the future.