Biomarker is an important tool in the study of marine organic geochemistry. Its development and application makes it possible to elucidate the process and mechanism of the organic matter in the ocean. Hydrocarbons are the most useful molecular markers. They are used as tracers in many aspects, such as source indication; the degradation of organic matter; diagensis process; environmental pollution and paleooceanic study, etc. They are studied in the estuaries, coastal area and deep sea to give the knowledge of marine organic geochemistry. The paper deals with the characteristics, development and application of biomarkers as well as their advantages and disadvantages. Biomarker is an important tool in the study of marine organic geochemistry. Its development and application makes it possible to elucidate the process and mechanism of the organic matter in the ocean. Hydrocarbons are the most useful molecular markers. , such as source indication; the degradation of organic matter; diagensis process; environmental pollution and paleooceanic study, etc. They are studied in the estuaries, coastal area and deep sea to give the knowledge of marine organic geochemistry. , development and application of biomarkers as well as their advantages and disadvantages.