Given the risks of casing corrosion failure and CO2 leakage at the casing-cement interface in CO2 sequestration technology, along with the limited purity of carbon sources and the unclear corrosion mechanisms and crevice corrosion sensitivity of L80-13Cr in this system, this study investigated the crevice corrosion sensitivity and mechanism of L80-13Cr steel in a simulated cement pore solution environment containing impurities (SO2, NO2, O2) at 10 MPa and 80 °C. The results indicated that, in the absence of crevice structures, carbon source impurities had no significant impact on corrosion behavior of L80-13Cr steel, with a very low uniform corrosion rate. The surface of the samples was predominantly covered by protective Cr-containing products. However, notable pitting behavior is observed. In the presence of crevice structures, localized corrosion occurred within the crevice. Additionally, pitting was more pronounced than in the absence of crevices. Besides Cr-containing products, FeCO3 was also formed within the crevice. The introduction of different concentrations of impurity gases did not significantly alter the crevice corrosion behavior. The destabilization and failure of the passivation film within the crevice pose a potential risk of L80-13Cr crevice corrosion failure and CO2 leakage in this system.