Modified starch tannage was synthesized by two steps. First step, a graft starch was synthesized by graft copolymerization of degraded starch with p-aminobenzene sulfonic acid and nekal using horseradish peroxidase (HRP)/H2O2 catalyze system. The effects of system pH, reaction temperature and amount of HRP on the graft efficient (GE) and graft percent (GP) were investigated and the maximum GE and GP of modified starch were obtained using 4 mg HRP/2.24 g H2O2 as catalyst at 35 for 3h under pH 7. The second step, the graft starch was oxidized by periodic acid to prepare modified starch tannage with dial dehyde.The effect of periodic acid on aldehyde groups content of graft starch was studied and it was found that the maximum content was at periodic acid concentration of 4 mol/L. The structure of modified starch tannage was characterized by FTIR, NMR and GPC. The shrink temperature (Ts)of tanned leather is 80.6 °C and the retanned leather has distinctive style of softness and flexibility.