Abstract: The effects of Pb<sup<2+</sup< on the metabolism of <em<Styela clava</em< were investigated using semi-static two compartment model. The results show that Pb<sup<2+</sup< could depress oxygen consumption rate of <em<S.clava;</em< 0.01mg/L Pb<sup<2+</sup< could improve its ammonia excretion rates, while the restrained effect occurrs when <em<S.clava</em< lies in higher concentration. Pb<sup<2+</sup< increases filtration rate of <em<S.clava</em< at the concentration of 0.01 and 0.05mg/L, while it is controlled 0.2mg/L. Restraining effect on O/N is correlative with Pb<sup<2+</sup< concentration. Pb<sup<2+</sup< could affect energy of metabolizing enzymes of <em<S.clava.</em< The depressing activities of alkaline phosphatase (AKP) as well as Na<sup<+</sup<-K<sup<+</sup<-ATPase are correlative with Pb<sup<2+</sup< concentration. When <em<S.clava</em< is exposed to Pb<sup<2+</sup<, the activities of SOD descend immediately and then increase again. This study suggests that the metabolism parameters of <em<S.clava</em< (O/N, AKP, Na<sup<+</sup<-K<sup<+</sup<-ATPase and SOD) could be used as markers of heavy metal pollution in offing marine space.