Abstract: The study of subsidence as geologic process is very important to understand oil migration and its occurrence in some basin areas. The subsidence rate and rapid deposition, sediment compaction and occurrence of overpressured zones are linked to one another in extensional faulted basins. The presence of locally high subsided and overpressured areas in Nanpu sag is related to the rapid sedimentation followed by depositional compaction and tectonic activities. The subsidence study consists of geohistorical analysis, which required the correction of sediment compaction and paleobathymetric depth determination through paleontologic studies and sea level changes. The subsidence of any stratigraphic horizon or any geological formation is caused by tectonics movements and the sediments and water loads, which led sediments to subside and compact. The subsidence analysis is useful for understanding regional tectonic history, the history of sea-level changes and thermal history of basin, which in turn, is essential for hydrocarbon studies. The subsidence analysis is very important key in sedimentary basin modeling in sense that sedimentary bodies are key recording information that allow making up good geologic appraisal, in the aim to understand the process of generation, migration and hydrocarbon accumulation. The subsidence analysis in Nanpu Sag shows that the highly subsided areas were controlled by structurally faulted zones, which coincided to the depocenters, where most of oil fields have been discovered.