The aliphatic hydrocarbons of 29 Tertiary argillaceous rock samples from eastern China have been examined by computerized gas chromatography-mass spectrometry. The steroid and triterpenoid components provide new information for the characterization of depositional environments, organic matter, and maturation of the source rocks. These samples contain gamaceranes, 8,14-open-hopanes, diterpenoid hydrocarbons, and diasteranes. The abundant gamaceranes correspond to the preference of even carbon atoms. The highest gamacerane occurs in the strongly reducing environment. The abundant diterpenoid hydrocarbons relate with the type III kerogen. These diterpenoid hydrocarbons are derived from higher plant forms. The threshold of oil formation can be correlated with the ratio of 20S (22S) and 20R (22R).