Diethyl phthalate ester (DEP) is a widely distributed organic contaminant in surface waters and soils, and its removal is important to human health and environmental safety. Montmorillonite is a cheap and abundant clay mineral. The Al/Fe pillared clays (Al/Fe-PILC) is an environmentally friendly catalytic material, which are synthesized by incorporating the hydroxyl polycations of Al and Fe into montmorillonite interlayers to increase surface and reactivity. In this study, the catalyst was characterized by XRD, BET, FTIR and HRTEM, and DEP degradation was studied by peroxymonosulfate (PMS) activated by Al/Fe-pillared clays. The results showed that DEP degradation rate after 24 h was about 92% and the ions of Fe were not detected in aqueous solution. DEP degradation was mainly attributed to the formed ?OH radicals. Further study found that common anions (Cl^-, NO₃^- and CO₃^2-) could not totally inhibit DEP degradation in the reaction system. Therefore, Al/Fe-PILCs is a promising catalyst in activating PMS for the remediation of organic contaminated water and soils.