Native corn starches were acid-treated at 53 °C for hours in HCl aqueous solution. The peak temperature (Tp) and heat of gelatinization (ΔHgel) before and after treatments were determined. The average particle size, TG and viscosity were measured. The results showed that the viscosity of corn starch decreased from 630mPa to 4.6mPa after acid treatment for 6h. The average particle size decreased and ΔHgel decreased obviously after acid modification.