Abstract: An environment with a weak corrosion tendency was used to promote the production of a limited metastable pitting distribution in 20CrMnTi steel. The law of metastable pitting initiation was investigated by using electrochemical noise. Using the ANSYS finite element method, the stress distribution and crack initiation risk of holes were analyzed and compared under different corrosion conditions. The results indicate that the pitting sensitivity of 20CrMnTi steel is high. The initiation of metastable pitting is preferentially concentrated at the edge of the impurity phase. The pitting induction period is obviously shortened and the pitting sensitivity increases with an increase in the Cl^- concentration. The increase in the nucleation rate induced by different Cl^- concentrations reduces the distance between pitting occurrences. Thus, surface microcracks readily connect and propagate pitting, thereby enhancing the risk of crack initiation.