Abstract: Acute Cu toxicity and Cu enrichment of Monodonta labio under Cu²⁺ stress and effects of Cu²⁺ on CAT and SOD activities in the hepatopancreas of Monodonta labio were studied.Results show that the 96 and 72 h half lethal concentration ρ(LC₅₀) of Cu²⁺ to Monodonta labio were 19.36 and 38.49 mg·L^-1,respectively.And the safe concentration of Cu²⁺(ρ_s) to Monodonta labio was 1.936 mg·L^-1.Monodonta labio enhanceed its Cu enrichment when the ρ(Cu²⁺) ranged from 0.25 to 4.00 mg·L^-1.An obvious dose-dependent effect of CuCu²⁺ was observed on Monodonta labio.When ρ(Cu²⁺)was 4.00 mg·L^-1,Cu²⁺ accumulation in Monodonta labio increased with the time of treatment,showing a obvious time-dependent effect.In all the Cu²⁺-treated groups CAT activity in hepatopancreas of Mondonta labio were higher than those in the control.In most of the treatments,the differences were highly significant(P<0.05) or extremely significant(P<0.01 or P<0.001).However,in some treatments,Monodonta labio showed lower hepatopancreas SOD activity than they did in the control.