Abstract: Since late Cretaceous, the Oujiang Sag has suffered from multi-stage tectonic movements and basin evolution with changing tectonic stress field, which leads to the formation of complex structural features and various structural styles. Through interpretation of both the new and old seismic data of the whole area, structural styles and their distribution pattern of the area are summarized, and the forming mechanism analyzed in this paper. According to the results, the main structural styles in the study area can be divided into three kinds, namely, extensional, compressive and composite styles. The extensional structures, which are developed in the western and eastern parts of the depression, can be further divided into horst-like, graben-like, half-graben-like, shovel-like and Domino-like styles, while the compressive structures, which are developed in the southwest of the depression, are mainly fault-nose structures. The complex structural styles are further divided into volcanic rocks, flower-like tectonics and inverted structures, which are main developed in the south-central part of the depression.