To study the antioxidative action of anisodmine (Ani) on H 2O 2 and generating system of free radicals FeCl 2 and ascorbic acid induced peroxidation of erythrocytes, we observed the variation of erythrocyte hemolysis induced by H 2O 2 before and after Ani were added to erythrocytes. Erythrocyte membrane microviscosity (EMMV) and erythrocyte lipid peroxide (LPO) on effect of generating system of free radicals were determined with fluorescence polarization method and TBA method before and after Ani added to erythrocytes. The results showed that Ani could significantly inhibit oxidative hemolysis of erythrocyte induced by H 2O 2 (100 mmol·L -1 ) hemolysis degree were 0 349±0 023 and 0 294±0 026,respectively(Ani were 1 5 and 2 0 mmol·L -1 ),but it was 0 448±0 034 in control group ( P<0 01 ). Ani (1 0,1 5 mmol·L -1 ) significantly inhibited the increased of erythrocyte LPO caused by FeCl 2 (0 1 mmol·L -1 ) and ascorbic acid (0 5 mmol·L -1 ) LPO were 5 468±0 174 and 4 896±0 192 respectively, control group was 6 181±0 212 μmol·L -1 ( P<0 01 ),and EMMV significantly decreased 0 363±0 023 poise and 0 299±0 015 poise respectively (Ani as 1 5, 2 0 mmol·L -1 ), control group was 0 481±0 026 poise (P<0 01) . It suggests that Ani could protect membrane lipid peroxidation caused by free radicals.