Abstract: Based on high resolution 2-D seismic section, the relationships between the formation and decomposition of gas hydrate and the tectonism in Shenhu area, South China Sea are studied, with layer form theory, the seismic response characteristics and sequence stratigraphic analysis. Adopting the layer form theory, the secondary sequence is divided into several tectonic periods by the strength of tectonic activity. The relationships between tectonism and sequence stratigraphy are established. The influence of tectonism to the formation and decomposition of natural gas hydrate is also discussed. On this basis, the relationships between natural gas hydrate accumulation mode and tectonic evolution model are further researched.