Oleoyl chloride was synthesized by oleic acid and thionyl dichloride (SOCl2), and then reacted with chitosan in dichloromethane to obtain the oleoyl chitosan. Novel water-soluble oleoyl acetyl chitosan (OACh) was synthesized using oleoyl chloride reacted with acetic anhydride in pyridine. The chemical structure of the OACh was characterized by FT-IR, 1H and 13C NMR. There existed the peaks at 1743.9 cm-1 (C=O) and 1658.1 cm-1(C=C) in FT-IR spectrum, and the peaks at 170.8, 171.6 and 172.5 ppm which were assigned to the C=O of the oleoyl and acetyl groups in 13C NMR spectrum. The results indicated that OACh had oleoyl as hydrophobic moieties and acetyl as hydrophilic moieties.