Abstract: The hydrocarbon structure and content analysis in sulfolane lean agent of aromatics extraction were determined by gas chromatography-mass spectrometry (GC/MS). The orthogonal test of three factors and three levels was used to determine the best chromatographic conditions. According to the obtained mass spectrum analysis, combining with mass spectrometry standard library searching and the hydrocarbon components of standard sample retention time, the hydrocarbon component structure could be determined under the scan mode. Each hydrocarbon component content was determined using internal standard method with n-octane as internal standard substance under the scan mode. The standard solution was prepared， and the relative volume correction factors of the hydrocarbon components were determined. The relative standard deviaton of sample hydrocarbon content is less than 5%, the recovery rate is 91%—109%, and the analysis time is about 14 min. Compared with traditional distillation method, the method is more precise, sensitive, rapid, simple without environmental pollution.