In the marine environment, the corrosion of steel bars caused by chloride ion intrusion is the main reason affecting the service life of reinforced concrete structures. Therefore, it is very important to propose a durability model to describe chloride ion intrusion to accurately predict the service life of port concrete structures. In this paper, MATLAB software is used to simulate the propagation process of chloride ions in reinforced concrete structures, and the obtained data is modeled by Gamma process, and a new method for predicting the durability life of reinforced concrete under chloride ion erosion is proposed. According to Fick's second law, the theoretical benchmark model of chloride ion diffusion in concrete is established. At the same time, the finite difference method and Monte Carlo method are used to obtain the chloride ion concentration data and structural durability data of the structural reinforcement surface under the action of multiple factors, and the histogram is made, which is compared with the theoretical curve of the durability life probability density function based on the Gamma process to prove the feasibility of the new method. The results show that the theoretical curve is in good agreement with the histogram, which indicates the accuracy and reliability of the durability model of reinforced concrete structures in the chloride salt erosion environment based on the Gamma process. The results can provide some reference for ensuring that the port concrete structure meets the applicability and safety requirements during the expected service period.