Abstract: Pillared alkaline Ca-bentonite samples were prepared with organic amine and non-ionic surfactant and they were used as deacidification agent to remove acid from high acid value 650SN and other heavy lube base oil. Factors influencing the acid removal of lube base oil, such as the layer structure and composition of deacidification agent, as well as agent dosage, treating temperature and time were studied. Test results showed that pillared alkaline Ca-bentonite sample prepared with clay/CaO mass ratio of 5/3 exhibited the best acid removal rate; using said sample with a dosage of 1.5% (based on the mass of base oil), treating at 80℃ for 4 h, the acid value of 650SN lube base oil dropped from 0.109 8 mgKOH/g to 0.023 9 mgKOH/g. Compared with conventional alkaline bentonite, pillared alkaline Ca-bentonite possess better deacidification efficiency, less consumption and good adaptability to different lube base oil.