The Dongpu Depression is a sub-tectonic unit of the Bohai Bay Basin. In the depression, four sets of salt rock  developed in two depositional cycles of the Paleogene, which occurred respectively in the fourth submember(S34),third submember(S33) and second submember(S32) of member III(S3) of  the Shahejie Formation, and member I of the Shahejie Formation (S1 ) . They are mainly distributed in the north part of the Dongpu Depression. In the center of the depression, salt rock is the thickest. Every set of salt contains many salt rhythms,  and each rhythm is composed of salt bed and mud bed. Laterally, salts grade into mudstones and sandstondes. The salt is formed in deep basin in arid climate. The salt material is derived from the uprising brine from deep underground. Layered brine is the basic form for the formation of salt. The upwelling path of the brine is large basement faults. Magmatism provides the dynamic force. Because of insulation of the salt layers, the temperature and pressure beneath should be affected, and this will quicken the maturation and evolution of organic matter. Salt is excellent cap-rock, witch is plastic under high temperature and pressure. Previous exploration showed that the lithologic reservoir is closely related with salt deposition. So for further exploration, it is very important to understand the distribution laws of the salts in the Dongpu Depression.