The acetalization and ketalization of various aldehydes and ketones with alcohols by using dealuminated USY(ultrastable Y-type zeolite) as catalyst were studied. The influences of silica/alumina ratio in the catalyst, catalyst amount and reaction time on the reaction were investigated. It is showed that the dealuminated USY is a high active catalyst for acetalization and ketaliz ation and its high activity can be readily returned to original by heating at 500 ℃ for 5 hours.