Abstract: High-performance steels have extremely high toughness and fatigue properties, correspondingly the controlling requirements of inclusions on average particle size, particle size distribution and number density are demanding. The oxides in additive manufacturing samples are ineffectively controlled and then affect the mechanical properties, due to the unavoidable increasing of oxygen content in the process of powder preparation. Therefore, the formation, characteristics and influence of oxides in additive manufacturing steels should be clarified, and then control optimizations are performed for compositions and technological process based on the oxygen content in powder, to obtain fine and dispersed oxides and finally realizing the harmless control of oxides. In this paper, the research progress of oxides in additive manufacturing steels is reviewed, 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 ideas to realize the harmless control of oxides are described, in order to provide references for the future research on the harmless control of oxides in the process of metal additive manufacturing.