Objective The reduction process of CuO with atmospheric pressure plasma jet was mainly influenced by different plasma gas and reduction time. And above two influence factors were discussed in this article. Methods Plasma jet was used to scan the surface of samples. The microstructure and phase composition were studied by SEM and XRD analysis after the reduction process. Results The reduction productsconsisted of Cu4O3 and Cu3O when using N2+decomposed NH3, whose valence state was lower than other reduction product Cu2O.Because the decomposed NH3 get excited hydrogen molecules easily after ionization, inspire, dissociative. The results show that main reduction product consisted of Cu3O at 40s,whose valence state is lower than that of CuO.Metastable phase Cu3O was gradually transformed into a relatively stable phase Cu2O as time went by. With the reduction time extending, Cu was segregated as time reached to 100s.ConclusionN2+decomposed NH3 had better reducibility than other gas medium. With increasein reduction time,copper ion valence was decreased and the Cu3O phase was transformed from metastable state into a relatively stable state. During the reduction process, the high energy electrons had the heating effect on the CuO particles, and the active particles in the excited state played a major role in the reduction.