The acute toxicity of Cu²⁺ and the changes of antioxidant enzyme of Chinese sturgeon（Acipenser sinensis Gray）were studied by the static test method. According to this LC₅₀，the experiment concentrations of CuSO₄ were set up at 0，0.005 mg/L，0.01 mg/L and 0.015 mg/L and the exposure time were set up at 24 h，48 h，72 h and 96 h. The results showed that copper was a drastic toxicant；the 24 h，48 h，72 h and 96 h median lethal concentrations of copper were 0.0593 2 mg/L，0.034 0 mg/L，0.028 3 mg/L and 0.021 7 mg/L respectively，the safe concentration of these metal was 0.002 17 mg/L. The activities of SOD，CAT and GSH-PX in the liver tissues of Chinese Sturgeon were restrained obviously within 24 h，but the activities recovered gradually from24 to 48 h，the activities decreased after 48 h，and it was lower than that of the contro1 group. The changes of the activities of SOD，CAT and GSH-PX indicated the damage degree of Chinese Sturgeon by Cu^2+.