Covert fault zone refers to the weak deformation structural zone in the cap rock caused by the inherited activity of the basement fault or the shear effect of the cap rock. It is a weak deformation structural zone before the formation of the main fault plane. The formation mechanism and evolution degree of covert fault zone are different, and its structural characteristics and structural types are also different. This paper attempts to reveal the differences in characteristics, formation mechanism and reservoir control between Wangjiagang covert fault zone and Bamianhe covert fault zone located in the south slope of Dongying Sag, Bohai Bay Basin. Methods: In this paper, by using fault distribution maps in different periods and 3-dimensional seismic profiles, the deformation characteristics of Wangjiagang covert fault zone and Bamianhe covert fault zone on plane and section are analyzed. In addition, the structural physical simulation experiment of extension-strike slip movement of basement fault at different direction angles α (the angle between extensional movement and strike slip movement in the horizontal direction) is designed to study the included angle α of their respective extension-strike slip movement directions, so as to analyze the difference between the formation mechanism of Wangjiagang and Bamianhe fault trend zone. Results: The Wangjiagang and Bamianhe covert fault zones in the south slope of Dongying sag are composed of a series of small en echelon faults, which are characterized by wide upper and narrow lower parts, and converging to the main strike slip faults in the lower part. Because there is no main fault plane in the shallow layer, it is also called recessive fault zone. Its formation mechanism and deformation degree are different, the number and nature of traps are different, and the ability to enrich oil and gas is also different. The results of structural physical simulation show that both Wangjiagang and Bamianhe covert fault zones are formed by strike slip-extension dual activity of basement faults. The angle between strike slip-extension direction is different: the former is 40° to 50° and the latter is about 20°. The Wangjiagang covert fault zone is in juvenile stage of fault zone development, with weak deformation, small fault zone width and small fault density; Bamianhe covert fault zone is in the young stage, with strong deformation degree, wide fault zone, high fault density, a large number of fault related traps, and higher oil and gas accumulation capacity than the former. Conclusions: According to the evolution stage, development characteristics and source-reservoir matching relationship of covert fault zone, it is considered that the deformation intensity of covert fault zone is the key factor to control the degree of hydrocarbon enrichment. The hydrocarbon accumulation model of Wangjiagang covert fault zone is “ juvenile stage weak deformation-single source depression hydrocarbon accumulation model”, and Bamianhe covert fault zone is “young stage strong deformation-double source depressions hydrocarbon accumulation model”.