The sequence stratigraphy and sedimentary system of the Early Cretaceous of subbasin of ceName w:st="on">Hailaer Basin have been studied by employing seismic, well log and drilling core data. The principles of divided sequence and identify marks of sequence boundary have been described. On the basis of the identification and correlation of sequence stratigraphic units, the object stratum has been divided into four third-order sequences. The paper analyzes the main cause of each sequence in detail and sums up different characteristics of various sequences developed pattern.