Abstract: The distribution pattern and diffusion coefficient of Cl^- in ultra-high-strength shotcrete and high-strength cement-based grout in chloride environment were studied through indoor immersion test in 5% (mass fraction) NaCl solution (360 d). The results show that under long-term immersion conditions of chloride salts, the diffusion of Cl^- in two high-performance cement-based materials followed Fick's second law. The surface Cl^- content increased with the extension of erosion age, while the Cl^- diffusion coefficient decreased exponentially with erosion age. Time varying models of Cl^- diffusion coefficients were established for both materials. The anti chloride ion erosion performance of ultra-high-strength shotcrete is superior to that of high-strength cement-based grout.