Abstract: The steranes, terpenoids and aromatic compounds from source rocks of Cretaceous Laiyang formation in Jiaolai basin were measured by means of technologies of biomarkers analysis, along with discussion of organic matter constituents, sedimentary environment and maturity of the source rocks. Study results show that the depositional environment for source rocks development is a reducing brackish water-saline half deep lake-deep lake one; the organic source materials originated from lower aquatic organ-isms (especially protist and bacterium) mixed with few terrestrial higher plants; the source rocks have maturities of entering oil threshold, such as that Xiaoxianzhuang member is characterized by high maturity and up to late maturity; Shuinan member is just in stage of the best oil generation.

Key words: Jiaolai basin, Cretaceous, source rock, biomarker compound