The selective oxidation process of dual‐phase 1180 steel was investigated in this study. Annealing was carried out in Cr/Cr2O3 Rhines pack at 820°C for 60, 120, and 240 s, under the oxygen partial pressures of 10−23, 10−25, and 10−29 atm, respectively. Field emission scanning electron microscopy (FE‐SEM), electron backscattered diffraction (EBSD), and X‐ray photoelectron spectroscopy (XPS) were used to analyze the experimental results. The oxides involved SiO2, MnO, MnSiO3, Mn2SiO4, and MnCr2O4. The amount of oxides augmented along with the increasing oxygen partial pressure. The Fe–Mn–Cr–Si–C–O2 oxidation diagram was calculated by thermodynamic software and was used to explain the selective oxidation process of dual‐phase 1180 steel. Experimental results combined with the thermodynamic computations well.