Acorn oxidized starch was prepared by using hydrogen peroxide as oxidant and Cu2+ as catalyst, and the effects of pH value, oxidant dosage, catalyst dosage, reaction temperature and reaction time on the carbonyl and carboxyl mass fractions of acorn oxidized starch were investigated. The results showed that the optimal reaction conditions were: reaction temperature 45 °C, reaction time 3 h, pH=8, H2O2 dosage was 20% (relative to starch dry weight, the same below), under this condition, when the catalyst dosage was 0.052 4% (relative to starch dry weight mass), acorn oxidized starch with carboxyl mass fraction of 0.914 0% was prepared. When the catalyst dosage was 0.124 4%, an acorn oxide starch with a carbonyl mass fraction of 0.918 3% was prepared.