Abstract: JZ)Distribution of overpressure in Dongpu depression is limited both in layer and plane section,the first overpressure is presented in SHA-3 layer vertically,a pattern of two concaves with one convex and one band is formed on the plane.The development and distribution of gypsum salt,the gravity load of the thick gypsum salt layer,the closed fault and the steady constructional and evolutionary conditions are favorable for the formation and conservation of overpressure,the diagenesis and dehydration of gypsum salt layer,the hydrothermal effect,the generation of hydrocarbon,supercharging effect from clay minerals conversion are the essential factors to form the extremelyhigh reservoir pressure.Through analysis,the following recognition can be drawn,overpressure plays a very important role in the aspect of reservoir sealing,reservoir porosity-permeability performance,fluid migration and episodic petroleum accumulation in oil and gas enrichment of Dongpu depression,overpressure is one of the basic element for the formation of reservoir.