ZnO/Al2O3 catalyst was prepared by an impregnation method and applied in the deacidification of 4th vacuum gas oil through the esterification with glycol. The catalyst phases were identified by XRD and it indicated that less calcining time was more benefit for the active component ZnO. The surface acid amount of the catalysts was analyzed by NH3-TPD, the catalyst calcined in 1.0 h had more surface acid amount which reached up to 0.415 mmol/g. The effects of the catalyst calcining time、catalyst dosage，glycol dosage，reaction temperature and reaction time on the deacidification were investigated. The vacuum gas oils before and after the deacidification were characterized by means of FTIR. The results showed that the ZnO/Al2O3 which was incandesced 1hour exhibited excellent catalytic activity for the esterification. Under the selected reaction conditions of vacuum gas oil dosage 40 g，the catalyst dosage 2.5% (w)(based on the vacuum gas oil，the same below), glycol dosage 4.0% (w)，reaction temperature 250 ℃ and reaction time 1.0 h，the acid removal rate reached 92.43%.The catalyst used five times and the deacidification rate reached to 92% which appeared good catalytic activity and stability. The FTIR results showed that naphthenic acids in the vacuum gas oil reacted with glycol into corresponding esters，which was also proved by 13C NMR，so the acids were mostly eliminated. Comparison of the part physicochemical indexes before and after the deacidification indicated that，the acids in the vacuum gas oil was greatly decreased after the catalytic esterification which drop from 2.51 to 0.19 KOH/g, and the other main physicochemical properties after the deacidification varied a little.