Abstract: In order to improve the hydrophobilicity of raw starch, lauric acid was grafted on starch through CALB lipase-catalyzed reaction in \[BMIM\]BF4 ionic liquid. Firstly, the structure of modified starch was tested with 1H NMR, it showed that the lauric acid was successfully grafted on starch. Secondly, the effect of different reaction conditions on the DS values of modified starch was studied in detail. Results showed that a better synthesis condition for laurate starch was as follows: lipase dosage 0.2 g, lauric acid/ AGU=3:1, temperature 60℃，time 4 h. Finally, the hydrophobilicity of modified starch was tested through water contact angle. Results showed that the hydrophobicity of modified starch was significantly improved and increased with DS values. 

Key words: lipase, starch, lauric acid, ionic liquid