Abstract: Octenyl succinic anhydride esterified waxy corn starches(OSAS)with different molecular weights were prepared by using waxy corn starch as a raw material,octenyl succinic anhydride(OSA)as an esterifying agent,β-amylase as an enzymolysis reagent. And its physicochemical properties were also determined. The results showed that OSAS with different molecular weights(1.0×10⁴~2.0×10⁵ Da)viscosity within the range of 0.0035~0.0010 Pa·s decreased significantly(P<0.05)as the molecular weights decreasing,the paste transparency decreased from 28.6% to 23.1%. The retrogradation and swelling degree of OSAS were also decreased with the reduction in molecular weights.It revealed that the esterification of waxy corn starch with succinic anhydride occurred mainly on surface of the starch granules,and new groups would not be introduced by the enzymatic treatment. This study initially revealed the relationship between the molecular weight of OSAS and its physicochemical properties.