Abstract: Several problems in the study of oil and gas preservation and their commercial potential in marine sequences of South China should include as follows:(1) Areas near the ancient petroleum pools,the large and high anticlines at the edge of basins and the uplifted blocks between sags are not ideal locations for discovery of large oilfield in South China;(2) Conditions of petroleum preservation were very complicated;(3) The properties of hydrogeology could be used to evaluate the preservation condition;and (4) The sedimentation,burial history and geothermal evolution should be studied in detail,and the hydrocarbon generation,migration and accumulation should be analyzed in accordance with its geological settings.On basis of study of regional tectonics,special concerns should be put in the two foreland basins located in the north and south respectively.