In this paper, two types of modified hydrotalcites (MHT) were incorporated into cement mortars with two dosage levels (replacing 5% and 10% cement by mass).Designated testing programme including strength test, porosity test, and rapid chloride migration and diffusion test were employed to investigate the effect of modified hydrotalcites on chloride penetration in cement mortar.The results based on these tests showed the incorporation of MHT-pAB at 5% dosage in mortar specimens produced a notably improved chloride diffusion resistance with no or minor influence on the development of mechanical strength.