Sulfate attack is an important factor contributing to the durability damage of concrete structures in coastal and salt-lake areas. In order to explore the interaction between sulfate erosion and concrete damage, the damage function was introduced in Fick's Second Law, and the diffusion-reaction-damage model of the sulfate ion erosion process in concrete was established considering the chemical reaction of the sulfate ion transport process. The three-phase meso-model of concrete was constructed by self-programming and numerical simulation was carried out. The simulation results are in good agreement with the experimental results, which indicates that the numerical model considering concrete damage can effectively describe the diffusion behavior of sulfate ions in concrete. The study showed that the free sulfate ion concentration and the bound sulfate ion concentration increased gradually with the increase of erosion time, but the increase in magnitude decreased, and the ion concentration at 5 mm increased 3.39 and 1.99 times at 180 days of erosion compared with 120 days of erosion, respectively. The bound sulfate ion concentration variation tends to be linear near the eroded surface. An appropriate increase in the water-cement ratio can delay the time of damage occurrence. When the water-cement ratio of 0.4 concrete damage value reaches 1 to start damage, the water-cement ratio of 0.6 and 0.7 concrete is in the filling enhancement stage, the damage value is 0.77 and 0.83 respectively. The simulation results can provide theoretical guidance for improving durability and prolonging the service life of concrete structures in a sulfate environment.