As the sulfate ions react with the hydration products of concrete material in the diffusion process, the coefficient of chemical reaction degradation effect of diffusion coefficient is introduced to the equation of diffusion and the deterministic theory model of sulfate ion diffusion is established based on influencing factor of chemical reaction being taken into consideration. Compared with the test result, the present model can be used to predict the mean value of sulfate ion concentration and it solves the problem of adaptability of Fick's second law of diffusion in concrete. Considering the micro holes with randomness at the beginning of the formation of concrete material, the Gaussian random distribution was used to describe the initial diffusion coefficient and the stochastic theory model of sulfate ion diffusion is established considering the influencing factor of chemical reaction. Compared with the test result, the present model can be used to predict the range of sulfate ion concentration.