Abstract: A series ofoctenyl-succinic anhydride (OSA)-modified starch with different degree of substitution (DS) were prepared using amorphous waxy corn starch and OSA,and then characterized by FT-IR and ¹HNMR.The relationship between the reaction efficiency(RE),internal structure,DS,weight-average molar weight(Mw) and the emulsibility,embedding rate of OSA-modified starch was investigated. Experimental results showed that the RE of amorphous starch with OSA and DS of amorphous OSA-modified starch were improved obviouslycompared with that of original starch. The emulsification and embedding properties of amorphous OSA-modified starch were significantly higher than that of the crystalline OSA-modified starch with similar DS,the EA,ES and embedding rate of the amorphous OSA-modified starch were 68%,67.3% and 55.2%, respectively.The emulsifying activity (EA) and emulsion stability (ES) of amorphous OSA-modified starch had no obvious change with the increasing of the DS and Mw of OSA-modified starch,while the embedding rate increased gradually.