Abstract: The Gaoyou Sag is an oil and gas-bearing sag with higher exploration degree in the Subei Basin.In recent years,the exploration targets have gradually shifted to these in the area with low S/N ratio and lithologic traps of deep sag belt.Based on the further structural cognition,dealing with the relation among structural styles,seismic data and drilling data,and solving the contradiction among them are significant for fine exploration in mature exploration areas.Simultaneously,the study on palaeo-structure background and palaeo-geography could guide the lithologic reservoir exploration of the unknown district,which is an effective thinking.Integrated with the structural geologic theory,through the research on the structural style of the complex faults in the Gaoyou Sag and the changing of the interpretation scheme for complex data area,new cognition has been summarized in the complex fault belt and north slope area in the Gaoyou Sag.Through the study on the relation between structural background and lithologic reservoir,the exploration direction for the subtle reservoir in the deep sag belt of the Gaoyou Sag is pointed out.