Abstract: The ultraviolet spectrophotometry is used to analyze aromatics and their derivatives. Taking benzene, naphthalene and phenanthrene as representative substances, n-hexane as solvent, the photon absorbing intensity of the substances is measured at 5 characteristic wavelengths. The results show the detection limit of 12.9×10^-9-20.5×10^-9, accuracy of standard-addition in blank 98.9%-101.4% and precision 3.73%-4.51%, and the standard recovery analysis of practical samples basically meets the requirements. The analysis testing method is optimized, with low pollution to environment, low toxicity to human body and high safety, which both reduces cost and improves efficiency. The method is simple and feasible, with high accuracy and precision, and can meet the requirements for analysis and testing of geological industry, suitable for mass analysis testing of aromatics in oil-gas geochemical samples.