Abstract: The most difficult thing in oil-gas-source rock correlation with fingerprints of light hydrocarbons is obtainment of light hydrocarbon extracted from source rocks. With a low boiling-point solvent, rock samples was extracted in a closed pot and analysed by high resolution gas chromatography using capillary columns. The results showed that this method could give out information of C₅ to C₃₁⁺, and could discrimanete over 100 hydrocarbons between C₅ and C₁₀ to satisfy the study of petroleum geology. It is ideal for correlation among oil, gas and source rocks.