Abstract: By use of gas chromatograph(GC) and pulse flame photometric detector(PFPD),after series of conditional experiments,the GC-PFPD analytical method for thiophenic compounds in oil and source rock has been established.Thanks to this method,the low-abundance 7 benzothiophenic compounds,19 dibenzothiophenic compounds and other sulf-aromatic hydrocarbons in oil and source rock are detected,with better precision than the GC-MS method.In application of this method,it has indicated that for the thiophenic compounds of crude oil and source rock in the Jiyang Depression of the Bohai Bay Basin,the dibenzothiophenic compounds are predominant and the content of benzothiophenic compounds is very low.The 'V' type distribution of the four methyl-dibenzothiophenic compounds is not only for carbonate rock,but also for mudstone deposited in salt water.And the distribution of the 4 compounds is influenced by both sedimentary environment and thermal evolution of t source rocks.