Abstract: According to the characteristics of stratigraphic development, the slope of the southern section of Liaohe west sag is divided into two structural zones: Bijialing eastern slope and Hudong slope. Taking the sediment formation process as the main line, this paper summarizes the research methods of "source-channelconverge" system to control the distribution of fan body. Firstly, it is clear that Huludao uplift is a branch of marginal uplift in Bohai bay basin and has the ability of continuous source supply. Secondly, several U and V shaped gullies are identified in the Hudong slope area with seismic reflection characteristics, and two main channels are formed in the direction of the basin, corresponding to two fan bodies. The depositional period of the third member of Shahejie formation in Bijialing eastern slope was controlled by paleogeomorphology and the depositional source was mainly from the north to the east. Ultimately, by using the method of artificial seismic phase identification, wedge-shaped reflected seismic phase, super reflected seismic phase, foreintegrating reflected seismic phase and parallel reflected seismic phase are identified in Bijialing eastern slope.By using limited drilling information, the successive development of alluvial fan-fan delta sedimentary system in Shahejie period in this area is made clear.