Abstract: Taking purple yam skin as the experimental material, cellulase and pectinase were selected to comparatively analyze extraction effect of purple yam skin, and the optmium technology conditions of the cellulase extraction of purple yam skin dioscin were optimized by using the orthogonal experiment based on the results of single factor test.Results showed the optimum condition were as follows: cellulose amount 2.0%, material-solvent ratio 1 ∶ 10 ( g/m L) , enzymolysis time 60 min, enzymolysis temperature 40 ℃. Under such conditions, the yield of dioscin was ( 8.77 ± 0.89) mg/100 g. Dioscin from purple yam skin showed significant antioxidant capacity, and half inhibition concentrations ( IC50) of DPPH·and that of·OH were 0.276 mg/m L and 0.430 mg/m L respectively, the scavenging abilities were slightly weaker than vitamin C.