Abstract: Zhongjiannan basin is a Cenozoic sedimentary basin developed in the west continental margin of the South China Sea and mostly inside the territory of China,and confined by the traditional boundary line of the country. With vast area and considerable sedimentary thickness, the basin has preferable perspective of hydrocarbon. As a composite basin, it underwent fault subsidence in the early time and then followed strike-slip reformation. The structural evolution of the basin has gone through three steps:①fault subsidence,with extensional structures developed;②strike-slip inversion,with strike-slip and extrusion structural styles formed accordingly;③regional subsidence,with vertical sedimentation mainly occurring and no obvious structural styles coming into being. Based on the interpretation of nearly 10 000 km seismic data of the basin, some main structural styles and their relation to hydrocarbon accumulation were comprehensively analyzed.