Raffinose long-chain fatty acid monoester, acylated at the 1”-and 6”- positions, was synthesized in dimethylsulfoxide by the acylation of raffinose with methyl laurate under reduced pressure with ultrasound irradiation. TLC analysis of 4μL reaction mixture were carried out on silica gel G plates using chloroform-methanol-aceticacid (V/V/V, 75:25:7) as eluent. Spots were located by spraying with 10% of phosphomolybdic acid hydrate in ethanol and heated at 105 ℃ for 10min. The product was then separated with silica gel column chromatography by dissolving 1 g sample in eluent and then eluted by chloroform-methanol-acetic acid on a 15 mm × 700 mm silica gel column (200~300 mesh) at flow rate of 1 mL/min. The eluent of 1 bottle/10 min was collected and the purified products were analyzed by HPLC, IR, MS and NMR, and identified as 1’’-O-lauroylraffinose and 6’’-O-lauroylraffinose. The two lauroylraffinose isomerides had similar solubility in polar solvent and high thermal stability.