Hydrogen peroxide (H2O2) oxidized maltodextrin was prepared as the ligand for aluminum–zirconium complex tanning. The effects of catalyst dosage, initiation temperature, and H2O2 dosage on maltodextrin oxidation were investigated. FT-IR analysis demonstrated that carboxyl groups were successfully introduced into oxidized maltodextrin. The carboxyl content and degradation degree of oxidized maltodextrin increased with the increase of H2O2 dosage. Maltodextrin oxidized by 40% H2O2 and 0.015% Cu–Fe catalyst at an initiation temperature of 70°C (OD-40) with moderate carboxyl group (6.75 mmol/g) and molecular weight (Mw 450) promoted the penetration and fixation of aluminum–zirconium salts in leather and showed better tanning performance, such as hydrothermal stability and porosity of leather, than traditional citric acid ligand.