Starch benzoate ( SB) was prepared from native corn starch in aqueous phase and characterized by FTIＲ，SEM，Xray diffraction，contact angle measurement and emulsifying ability measurement． The optimal conditions are as follows: the molar ratio of benzoyl chloride to native starch is 3. 0， the molar ratio of sodium hydroxide to benzoyl chloride is 1. 95，reaction temperature，24℃，and reaction time，1h． According to FTIＲ，the benzoyl group has grafted onto native starch chain unit while hydroxyl groups gradually disappeared with the increase of DS． SEM showed morphology of granules was retained but became rough and cracked after the modification． Xray diffraction pattern indicated that crystalline regions of SB were damaged while sub crystalline regions remained relatively complete． The results of contact angle measurement and emulsifying ability measurement proved that SB possesses much better hydrophobicity and emulsifiability than native starch． The TG curves suggest that SB has poorer ability to retain water and to stand temperature in comparison with native starch．