The effect of pretreatment on the properties of starch oxidation was studied. The raw starch was pretreated and then oxidized with fenton. The influence of pretreatment conditions such as temperature, time and pH on the crystallinity of starch as well as the properties of the oxidized cassava starch were studied. The result showed that pretreated oxidized starch paste had good freeze-thaw stability, high transparency, and better mold inhibition; the viscosity, gelatinization and solubility of oxidized starch were decreased. This study provides theoretical guidance for the application of oxidized starch in many fields.