In the late 1980’s stable carbon isotopic geochemistry of biomarker compounds appeared as a new field of scientific research. The original interpretation of carbon isotopic compositions of individual biomarker compounds is critical to the new field. This paper comprehensively discusses carbon isotopic variations of lipid compounds in the biosynthesis, carbon isotopic fractionations in bacterial biosynthesis and carbon isotopic compositions of bacterial lipid compounds, attemping to provide useful imformation for the research of carbon isotopic geochemistry of biomarker compounds. Studied results show that the carbon isotopic variations of individual organic compounds in the same type of lipids or between different types of lipids are apparent due to carbon isotopic fractionations in the biosynthesis. The process of bacterial biosynthesis have a larger carbon isotopic fractionation compared to that of other biosynthesis, therefore the bacterial lipid compounds are strongly depeted in ¹³C.