Fluorescence spectroscopy of aromatic hydrocarbons in oil and gas samples has been studied. The contours and three dimensional fluorescence spectra of crude oil are obviously different from those of coal in distribution and composition of aromatic hydrocarbons. The light crude oil might obtain the features of coal if it lies in the atmosphere for several years. When rocks stemmed from terrestrial oils, there exists the peak of perylene in Constant -Wavelength Synchronous Fluorescence Spectroscopy (CWSLS); when rocks stemmed from marine oils, there is only the peak of benzene and naphthalene. Interfering factors in borehole can be recognized by fluorescence spectra. Constant-Energy Synchronous Fluorescence Spectroscopy(CESLS), a technique which involves the simultaneous scanning of both monochromators with a constant energy difference, was used to analyze the three-component aromatic hydrocarbon mixtures and the crude oil. More benefits over CWSLS were observed in both cases.