To investigate the binding capacity and mechanism of AFm and C3AH6 with Cl- ions, high purity AFm and C3AH6 were synthesized with C3A. The mineralogy and morphology of the products after reaction of AFm or C3AH6 with premixed and ingress Cl- ions, and the corresponding binding capacities were characterized. The results show that C3AH6 has a higher Cl- ions binding ability (i.e., up to 75%) with premixed Cl- ions than AFm (i.e., 17%), especially at a relatively low content of premixed Cl- ions. A reaction between Cl- ions and C3AH6 is faster than that between Cl- ions and AFm. The binding product generated by C3AH6 is Friedel’s salt, while those by AFm are Hc, Kuzel’s salt, Friedel’s salt and AFt, which depends on Cl- ions concentration and its introduced manners, via premixed or ingress Cl- ions.