Oil wells are mainly drilled in mid-deep strata in Nanpu sag. Deep strata is the exploration focus in future.Based on high-quality seismic velocity data，speed correlation method and Fillippone formula calculation method were applied synthetically to the prediction of pressure distribution in mid-deep strata of Nanpu sag. This study shows that：①in the vertical，the top interface of overpressure is between 3 000 and 3 500 meters in Nanpu sag. Overpressure is mainly located in the second member of Dongying Formation and the strata below，which can be roughly divided into middle overpressure system and deep overpressure system；②in the plane，overpressure center migrates from south-central part to north-central part of the sag with depth increasing. The overpressure center of the Dongying Formation mainly locates in central Linque sub-sag and south seabeach area. The overpressure center in the Shahejie Formation mainly distributes in north Gaoshangpu-Liuzan Structure，Laoyemiao and Nanpu Structure5. The results may not only reduce the cost of exploration and development risk，but also provide reference to the exploration of mid-deep lithologic oil-gas reservoir. In terms of pressure prediction method，speed correlation method has higher precision，which is suitable for pressure prediction in Nanpu sag.