Reinforced concrete structures located in coastal atmospheric areas are susceptible to harmful ions such as chloride ions and sulfate ions, resulting in a shortened service life of the structure. The pore size distribution of steam-cured and standard-cured concrete was studied through low-field nuclear magnetic resonance experiments, revealing the corrosion evolution law of chloride ions and sulfate ions on steam-cured concrete. The results indicate that compared to standard cured concrete, the harmless pore content of steam-cured concrete decreases, while the harmful and multi-harmful pore content increases, resulting in a higher degree of hydration. The compressive strength of steam-cured concrete is lower than that of standard-cured concrete. Adding a certain amount of mineral powder can significantly improve the resistance of steam-cured concrete to chloride ion corrosion. The greater the chloride ion binding ability, the smaller the chloride ion diffusion coefficient, and the lower the surface chloride ion concentration. When the content of mineral powder is 25%, the chloride ion diffusion coefficient of steam-cured concrete is low, indicating that the optimal pore size effect of the secondary hydration of mineral powder is achieved; As the amount of mineral powder increases, the reaction coefficient of sulfate ions gradually decreases. When the amount of mineral powder is 50%, the reaction coefficient of sulfate ions is the lowest due to the lowest content of calcium phase substances in concrete.