In this paper, we studied the growth of S. platensis in mimic Pb²⁺ polluted environment with different concentration from 10 to 80 mg·L^-1. The results showed that the growth rate of S. platensis was inhibited by Pb2+ above 20mg·^-1, S. platensis yellowed and died with Pb²⁺ concentration increasing and time going. The solvable protein, phycocynin and the ratio of phyco-cynin to carotenonid were all decreased. Each had a noticeable correlation with the Pb²⁺ concen-tration. Lower concentration of Pb²⁺ could decrease the photosyntheitc O₂ evolution of S. plat-ensis, yet the absorption spectrum of S. platensis was only seriously changed on high Pb²⁺ con-centration. Contents of O₂^- and MDA were also changed, each reached its maximum at 30mg·L^-1 and 40mg·L^-1. The activity of SOD was decreased obviiusly when above 20mg·L ^-1, but its relative activity was higher and quite steady at Pb²⁺ concentration from 20 to 50mg.L^-1.