The fluctuation of *OH concentration in Tubifex tubifex exposed to copper was investigated by Fluorospectrophotometry using terephthalic acid (TA) as *OH trapping agent. Catalase (CAT) activity in T. tubifex was quantified after 30 minutes contact with copper. Inactivation effect and lipid peroxidation produce malondialderhyde (MDA) of T. tubifex were also studied. Results showed that copper had significant inactivation effect on T. tsubifex. 100% inactivation efficiency was obtained when copper levels was 1 mg x L(-1). One of the inactivation mechanisms is inducing *OH increase in T. tubifex, which results in oxidative stress and lipid peroxidation. The increment of *OH concentration was 69.2% when copper lever was 0.05 mg x L(-1). The significant decrease of CAT activity showed copper could inhibit CAT activity to increase its oxidative stress to T. tubifex. Between 0.05-0.25 mg x L(-1), copper induced significant MDA increase, which meant lipid peroxidation. The changes of inactivation efficiency, *OH, CAT and MDA showed that the inactivation effect of copper on T. tubifex did not result only from oxidative stress and lipid peroxidation induced by *OH itself. Feasibility analysis of using copper to inactivate T. tubifex for water plant showed when sand filter was immersed by 1 mg x L(-1) copper for 30 min and then began backwashing, residual copper concentration was only 4.3 microg x L(-1).