Wuerxun depression is a secondary structural unit of Beier lake depression in Hailaer basin. It is located in the middle of the basin and has a high degree of exploration, with the gradual deepening of exploration degree, the previous studies on sequence division and sedimentary facies cannot meet the requirements of high-precision exploration. In this paper, the Nantun Formation is divided into three third-order sequences and eight fourth-order sequences through the study of high-resolution sequence stratigraphy in Wuerxun depression, in the study, firstly, multiple exploration wells with complete sequence development are selected in Wunan area of Wuerxun depression, because Wuerxun depression on the whole is characterized by complex structural features, multiple provenances, short provenances and rapid phase transformation, so we should try our best to make the distribution of preferred wells in all the fourth order structural zones, in order to facilitate the next step of stratigraphic correlation between the structural zones and the whole region. After that, the original sequence of all the selected wells is further subdivided according to the rock and electrical characteristics of single well, and a set of scheme for dividing the fourth-order sequence is determined. Finally, through the tracing of seismic horizon between exploration wells and the fine comparison of well and well seismic in the development area, the traceability and comparability of the newly divided fourth-order sequence are determined, and a set of reasonable fourth-order sequence division scheme in Wuerxun depression is finally determined, which effectively guides the geological oil and gas exploration deployment and lays a solid foundation.