Using viscosity and reducing sugar contents as the indexes,the effects of microwave pretreatment on liquification of corn starch at a high concentration were investigated,and its mechanism was analyzed.The results showed that,during the gelatinization and liquificaction of high concentration corn starch,the viscosity of microwave-treated starch paste was lower and the reducing sugar content was higher than the control one.Therefore,microwave pretreatment could lead to more efficient liquification of corn starch at a high concentration.This may due to the microwave pretreatment which caused surface area rough and holey,and lower the crystallinity of corn starch granule,resulting in higher rate of starch granule degradation by enzyme during the gelatinization.In addition,microwave pretreatment could also make some starch chains break to a certain extent.