Abstract: With exploration degree rising, lithological stratigraphic trape have become the main exploration targets in the Mesozoic and Cenozoic high-maturity basins. The study of sequential stratigraphy and sedimentary development of Langgu Depression is of great significance to further exploration of lithological stratigraphic traps in the depression. Based on joint 3D seismic data about Langgu Depression and guided by sequential stratigraphic theories, the Paleogene system of this depression is divided into 12 three-level sequences with each further divided into three area series of low level, high level and lake invasion. Influenced by structural movement, physical sources and climatic changes, a variety of infill patterns developed within the depression, forming various facies belts, such as fan delta, braided river delta, alluvial fan. The study points out that Daliuquan nose structural belt and the western belt of Hexiwu are favorable belts developed in the lithological stratigraphic traps in the depression. Es3 and the upper subsection of Es4 are favorable levels of the sand bodies in the depression, with development of braided river delta sand body of SQ3 low level system, near-bank underwater fan sand body of SQ6 low level system and fan delta sand body of SQ7 high level system, providing favorable reservoir space for lithological stratigraphic oil reservoirs