Abstract: With further development of Bohai sea area, the development strength of Paleogene complex fault block oilfield in Bohai sea has been increased. However, this kind of oil reservoir is influenced by multiple faults. The complex fault block oilfield is divided into a plurality of blocks. By the fault effect, the relation of oil and gas and water become very complex in this kind of oil reservoir. So the interpretation of fault system directly relates to the successful development of the oilfield. J oilfield is located in north low bulge of western Liaodong Bay. There are two groups of nearly north-south and east-west faults in the oilfield. Because of fault intersecting, the geological conditions are very perplexing in the J oilfield. In this paper, some technologies, such as seismic forward modeling and the seismic variance analysis etc, have been applied to the seismic interpretation of the Bohai complex oil reservoir. These technologies can resolve the difficulties in the seismic interpretation of J oilfield. The successful application of these technologies are advantageously directed the complex fault block oil field development. These experiences for the similar oil reservoir research are of good reference significance for complicated fault block.