Taiwan Strait Basin is commonly considered to be a good petroleum-bearing area. However, the former studies were all focused on the data from sedimentology and geophysical exploration, and no direct evidence from drilling or petroleum geochemistry can prove the existence of any economic oil or gas reservoirs in areas supposed to have good petroleum prospects. In this study, submarine near-surface geochemical exploration for oil and gas was conducted to reveal whether the hydrocarbon seepage is existent in these areas in the hope that it could further provide direct evidence for the existence of petroleum reservoirs at subsurface. The result indicates that the hydrocarbon seepage system do exist in this area, and the near-surface response of hydrocarbons in the sediments further indicate that the study area has a good petroleum prospect.