Abstract: Maxi subsag is one of the hydrocarbon-richest oil-generating subsags in Raoyang sag, which has abundant remaining resources. With increasing exploration, the third member of Shahejie Formation of low exploration degree, huge potential and lithologic reservoir- forming conditions becomes the important series of strata for further exploration. However, the third member of Shahejie Formation is diff icult to be explored, because of its complicated sedimentary features during sedimentary stage. This paper suggested analyzing reservoir-forming conditions again and looking for favorable lithologic exploration zones based on tectonic setting study, carrying out sequence stratigraphic research and confirming favorable lithologic exploration series of strata, comprehensively analyzing sedimentary facies and establishing multiple lithologic reservoir-forming mode, using full 3D interpretation techniques for meticulous interpretation and identifying lithologic traps, evaluating and optimizing exploration targets to implement drilling and exploration. Well Xi61x, Well Xi64x and Well Ma98 were drilled successfully in the lithologic traps of the western slope and the eastern fracture zone. In 2012, probable petroleum reserves submitted by Maxi area were 26.96 million tons. Exploration practice shows that the deep layers of oil-rich subsags are favorable targets for lithologic reservoir exploration.