Microscopic properties of a Pu-Fe mixed oxide (MOX) are investigated by means of single-particle approximations and a many-body theory. Calculation results demonstrate that Pu 5 f_{j =5/2}, 5 f_{j =7/2} components display conducting and insulating states, respectively. While for Fe 3 d electrons, e_g and t _{2 g} components both exhibit the conducting state. Intermediate and weak correlations emerge for Pu 5 f_{j =5/2}, 5 f_{j =7/2} regimes, respectively, while Fe 3 d e_g and t _{2 g} states both exhibit the strong correlation. Fe 3 d/Pu 5 f quasiparticle weights suggest that PuFeO ₃ has an orbital-dependent localization. jj and intermediate angular momentum coupling mechanisms are feasible for 5 f (Pu) and 3 d (Fe) states, respectively. 5 fⁿ configuration coupling produces an intermediate configuration (thus Pu having a mixed oxidation state), inducing quasiparticle multiplets. The quasiparticle band structure agrees with the spectra features inferred from the density of state. The relative lattice volume has no proportional or opposite trend with evolution of Pu 5 f&Fe 3 d occupancies. Duality of the electron localization, electron/valence/configuration fluctuation and intermediate configuration/valence/occupancy show that multi-scale features of the correlated materials could be modulated by means of various working conditions.