Abstract: Starch sodium dodecenyl succinate( SSDS) was successfully prepared using anhydrous sodium carbonate as a catalyst,dodecenly succinic anhydride( DDSA) as a esterification agent in the presence of a small amount of water.The effects of different reaction conditions on substitution degree of SSDS were investigated,such as dosage of anhydrous sodium carbonate,deionized water,DDSA,diluted multiples of DDSA,reaction temperature,reaction time. Structures of SSDS were characterized by FTIR and1 HNMR. Experimental results showed that the substitution degree of SSDS was up to 0.0224 when the amount of anhydrous sodium carbonate was 5%,the amount of deionized water was 20%,the amount of ethanol solution of DDSA was 10%,the diluted multiples of DDSA was 1.5 times,reaction temperature was 40 ℃ and reaction time was 6 h. The analysis of FTIR and1 HNMR showed that SSDS was successfully prepared.