Acute toxicity of the heavy metal copper and zinc with different density of quality to Longnose gudgeon was studied by static bioassays in this test. The results showed that the 24,48,72 and 96 -h LC50 values of copper and zinc to Longnose gudgeon were 0. 91mg/L, 0.69mg/L, 0. 56mg/L, 0. 49mg/L and 39.63 mg/L, 36. 06 mg/L, 32. 43 mg/L, 28.77 mg/L respectively, the safe concentrations were 0. 12 mg/L and 8.96 mg/ L. To Longnose gudgeon, copper was a high toxicant, while zinc was a low toxicant. The tolerance of Longnose gudgeon to copper was lower than that of zinc.