Abstract: A finite element simulation study on the changes of chemical substances in the crevice corrosion process of 316L austenitic stainless steel in NaCl solution was conducted. The reversible reaction with specified equilibrium constants in the COMSOL chemical interface was used to solve the equilibrium reactions occurring in the solution. These reactions were coupled with the Nernst-Planck interface of the third current distribution. This multi-physics coupling research method provides new ideas and means for the analysis of the crevice corrosion process. The crevice corrosion state was discussed through the distribution of various ion concentrations in the solution. The results show that this method can effectively calculate the transport of various chemical substances such as O₂, Cl^-, Fe²⁺, H⁺, etc. in the crevice and the chemical reactions that occur. The corrosion reaction rate near the crevice opening is significantly higher than that on both sides. The chloride ion content in the solution is significantly reduced due to the high concentration of hydroxide ions, which indicates that the crevice corrosion behavior of 316L is closely related to the solution pH value. This study help better predict and prevent the corrosion problem of stainless steel in specific environments in practical applications and improve the service life and reliability of stainless steel materials.