Study of hydrocarbon gases preserved in different states，including a free natural gas，an absorbed gas，an acid-dissolved gas and an oil-dissolved gas，is of very important theoretical and practical values for evaluating source rocks，recognizing natural gas origins，re- searching oil-gas mixtures，oil-gas source correlation and oil-gas exploration. Through natural gas geological research organized in the sixth，seventh and eighth five-year plans in China，great progress have been made in the research of the gases. In this paper research results，problems and prospects of the uses are summarized.