Cold worked CRAs (Corrosion Resistance Alloys) have been successfully used for corrosive sour gas wells for many years. However, the locally activated pitting and the consequential stress concentration is one of the main mechanisms of stress corrosion cracking failure of cold worked CRAs. The corrosion behavior of Ni-base alloy 028 was simulated in the environment with high temperatures and high partial pressures of H2S/CO2. The results show that the general corrosion of Ni-base alloy 028 was slight, but pitting corrosion happened on the surface of the alloy, and the pitting corrosion of the sample with precipitated phase was more obvious. The XPS results indicate that after corrosion, the element sulfur enriched only in the surface layer of the passive film, and the passive film which can protect the matrix was mainly composed of oxides and hydroxides. But the EDS analysis results of the cross section of pitting corrosion indicate that element sulfur enriched inside of the pitting, resulting in local acidification; consequently, the growth of the pitting was accelerated.