Based on GC-qqqMS/MS,a qualitative and quantitative analysis method for identifying characteristic markers in gasoline samples was established.According to the established method,different grades(#92,#95,#98)of gasoline samples collected from different regions(southern,central,northeastern,and northwestern China)were studied and analyzed.The results show that the gasolines can be classified by the relative contents of aromatics,naphthalene series,indene and other characteristic substances.On the basis of the high sensitivity and selectivity of GC-qqqMS/MS,the experiment has identified the characteristic substances,and used the characteristic-ratios methods as well as stoichiometric tools to study the grades and regional differences of gasoline products.It is conducive to the identification and classification of ILR in public security in fire cases,and can also meet the actual handling demand.