Abstract: The fault depression structure developed well, and had deeper depression, wide slope, many faults, lots of unconformity and many kinds of sandstone body in Ban-qiao sag. Studying the relationship between various kinds of sandstone body and structural geology, the subtle oil -gas reservoir have been found, which can be classified three types and six kinds: sandstone pinch out reservoir, isolated sandstone reservoir, fault lithologic reservoir, slope belt stratigraphic overlap reservoir, palaeo geomor-phology reservoir, complex reservoir. This article has also analyzed the characteristics of each subtle trap in Ban-qiao sag.