Abstract: Langgu sag is one of the hydrocarbon rich sags in Jizhong Depression, with high exploration degree. “Secondary exploration” was carried out in high-exploration-degree area and remarkable results were achieved in structural exploration. It is thought that lithostratigraphic exploration is a feasible way to f ind next target for fi nding large-scale reserves, based on 3D data sets, standing on abundant residual oil and gas resources and developing integrated geologic study. Tectonic inversion occurred during the depositional period of the f irst member of Shahejie Formation-Dongying Formation in Langgu sag, and sand bodies of early-deposition downdip pinchout were converted to updip pinchout, providing structural setting for forming lithostratigraphic traps. Eastern, northern and western provenances developed; sedimentary sand bodies of delta front, fan delta front and nearshore subaqueous fan grew well. Hydrocarbon translocation system of fracture surface, unconformity interface and sand bodies existed in this area. Multiple lithostratigraphic traps grew on steep slope zone, trough zone and gentle slope zone, having favorable reservoir forming conditions. Multiple favorable targets were conf irmed in the fl ank around Tongnan trough of fewer faults and simple tectonic setting, Daxing conglomerate bodies and western Hexiwu, which are the focus of further exploration.