Abstract: We introduce the establishment and optimization of capillary gas chromatography-flame ionization detection (FID) for analysis of acetylated oligosaccharides. Chemical and instrumental analysis of oligosaccharides requires derivating them into their derivatives. We used 1-methylimidazole as a catalyst and acetic anhydride as a reagent for acetylation of oligosaccharides. The acetylation and separation of acetylated products of sucrose, raffinose and stachyose were optimized and effectively separated by gas chromatography on a DB-15 capillary column and detected by an FID detector. The method is accurate, precise and has high recovery rate. The recovery rates for sucrose, raffinose and stachyose were all above 90%. The standard curves of oligosaccharide acetylated derivatives showed a high linearity in the range of 80 to 1 000 ng·μL^–1 concentrations. The linear correlation coefficients were 0.995 2 for sucrose, 0.995 7 for raffinose and 0.987 7 for stachyose. The method is suitable for analysis of target compounds in the food sciences, medicine and biological sciences, with the advantages of high reproducibility, minor sampling and chemical consumption and environmental friendliness.