Abstract: Focusing on the relationship between the characteristics of argillite and petroleum migration, the authors have studied and discussed the regularity between argillite compaction and the primary migration of oil/gas within the basin, on the basis of the data of a-coustic time and fluid pressure. It is suggested that low pressure zones or hydrostatic pressured zones are the orientation prefered by petroleum migration and accumulation, and therein the areas of petroleum enrichment. Pressure seals formed in the abnormal high-pressured zones are considered as important factors for the formation of gas pools while the release and disappearance of the pressure in the abnormal high pressured zone during argillite compaction and expansion caused by hydrocarbon generation are the driving forces for the primary migration.