In this research Spirulina subsala was firstly pretreated by paraquat (10μmol° L^-1) and H₂O₂ (2mmol° L^-1) to induce its antioxidant enzymes, then were treated under Pb₂₊ stress (40mg° L^-1).The results showed that the decreases of both grow th yield and photosynthesic rate of pretreated Spirulina subsalsa were less than those of the non-pretreated.Although the activities of SOD and CAT were also decreased, they were higher than those of the non-pretrea ted, and they inhibited the accumunation of O2 and M DA effectively.The range of POD increase was between those of the non-pretreated and the control.It could be concluded that induction could increase the antioxidant capacity, and could help Spirulina subsala resist Pb₂₊'s toxity.