Abstract: Heavy metal pollution is one of the most hazards of environmental pollution these years in fishery.With the development of industry and agriculture, a lot of heavy metal pollutants are released through various methods into the water body.Biological monitoring can reflect the environmental pollution conditions completely, sensitively and continuously.Culter alburnus Basilewsky is a widely exiting fish all over the whole country that with highly economic value.In order to estimate the acute toxicity and joint toxicity of heavy metal Cd²⁺,Zn²⁺ and Cr⁶⁺ toward C.alburnus Basilewsky, single chemical and mixture experiments were tested in still water at(22±1)℃.Resultsof single toxicity tests are as following: LC₅₀ of Cd²⁺ on C.alburnus in 24 h, 48 h, 72 h, 96 h were respectively 12.29,9.56,7.41 and 6.05 mg/L,LC₅₀ of Zn²⁺ were respectively 41.92,34.43,27.37 and 22.23 mg/L,LC₅₀ of Cr⁶⁺ were respectively 39.47,32.68,27.25 and 25.72 mg/L;the safety concentrations for Cd²⁺,Zn²⁺ and Cr⁶⁺ were respectively 0.605,2.223 and 2.572 mg/L.Joint toxicity experiments indicated that AI>0 of the coexistence of Cd²⁺/Zn²⁺ in 24 h, 48 h, 72 h, 96 h, as well as Zn²⁺/Cr⁶⁺ and Cd²⁺/Cr⁶⁺.Every coexistence group showed synergy.Among these groups, the joint toxicity of Zn²⁺/Cr⁶⁺ suggested the most intensive.