Abstract: It has been confirmed that the continental slope of Dongsha area in the northern South China Sea(SCS) is a prospecting area for gas hydrate.Sub-bottom profiling,due to its efficiency and high resolution,is widely applied in the investigation of gas hydrate by domestic and foreign scholars. In the paper, we selected two sub-bottom profile survey lines from the southwest Dongsha area in the northern SCS to reveal acoustic characteristics of shallow sediments.Shallow gas strata were divided and gas seepage phenomena observed from the sub-bottom profiles. It is speculated that there was deep gas hydrate decomposition and migration vertically or horizontally along faults.Shallow gas escaped around the gas seepage points.According to the availability of gas source, temperature and pressure combination and geological and biological evidence from the research area, it is inferred that the research area is favorable for gas hydrate formation.