Abstract: With Fenton reagent as oxidant to oxidize potato starch, the effect of pH, oxidized temperature, oxidized time, 30% H2O2dosage, FeSO4dosage on carboxyl content in oxidized starch were studied.Based on single factors experiments, the oxidation technology of potato starch was optimized through Box-Behnken, built and analyzed a mathematical model of the relationship between factors and content.Results showed that with the condition of 30% H2O2dosage of 25mL, pH 10 and oxidation temperature of 50℃, oxidized starch had 1.4590% carboxyl content, which was close to theoretical value of 1.4699%.It explained that regression model could precast carboxyl content of oxidized starch better.There were some holes on the surface of starch granule after oxidation through SEM.And carboxyl characteristic absorption peak was proved to exist by IR.