Abstract: After a study of the strata of the Early Cretaceous Quantou Formation in northern Liaoning,the authors propose a classification scheme of the depositional sequences of the Quantou Formation:two sequences,11cyclic sequences and20essential sequences,summarize four types of sequence classification and their criteria for recognition and recognize three sedimentary systems ,i.e.the lacustrine-deltaic dis-tributive channel sedimenta ry system,shallow-lacustrine sedimentary system and lake delta front sedimentary system.