The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18 MolVN high-nitrogen plastic mould steel was investigated.The microstructure,elemental distribution and Cr-depleted zone of different heat-treated samples were investigated by X-ray diffraction,electron probe microanalyzer analysis,and transmission electron microscopy.The corrosion resistance was evaluated using electrochemical measurements,and the analysis of passive film was carried out by X-ray photoelectron spectroscopy.The results indicated that the volume fraction of precipitates decreased,and the homogeneity of elements was improved with increasing austenitizing temperature.The degree of Cr-depleted zone around coarse M_(23)C_6 was severer than that around M_2N,and pitting corrosion initiated preferentially around M_(23)C_6.The corrosion resistance of the samples increased with the austenitizing temperature.With the increase in austenitizing temperature,the passive film was thickened and Cr(Ⅲ)_(Cr_2O_3) in the inner layer of passive film was enriched,which enhanced the corrosion resistance of the steel.The higher content of nitrogen in solid solution at higher austenitizing temperature contributed to the increased intensity of CrN and NH_3,leading to the increase in pH value in the pit,and promoting the repassivation of 55Cr18 MolVN steel. The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18 MolVN high-nitrogen plastic mold steel was investigated. Microstructure, elemental distribution and Cr-depleted zone of different heat-treated samples were investigated by X-ray diffraction, electron probe microanalyzer analysis, and transmission electron microscopy. the corrosion resistance was evaluated using electrochemical measurements, and the analysis of passive film was carried out by X-ray photoelectron spectroscopy. The results indicated that the volume fraction of precipitates decreased, and the homogeneity of elements was improved with increasing austenitizing temperature. The degree of Cr-depleted zone around coarse M_ (23) C_6 was severer than that around M_2N, and pitting-proof initiated preferentially around M_ (23) C_6. the corrosion resistance of the samples increased with the austenitizing temperature. With the increase in austenitizing temperature, the passive film was thicken ed and Cr (III) _ (Cr_2O_3) in the inner layer of passive film was enriched, which enhanced the corrosion resistance of the steel. higher content of nitrogen in solid solution at higher austenitizing temperature contributed to the increased intensity of CrN and NH_3 , leading to the increase in pH value in the pit, and promoting the repassivation of 55Cr18 MolVN steel.