Abstract: Under the conditions of water temperature of 25-27℃ and pH of 8.1-8.2, compounding the solution by nitazoxanide dissolved in dimethyl sulfoxide and using the hydrostatic test method, the acute toxicity of nitazoxanide on fingerings of large yellow croaker were studied. The test results showed that 24 h,48 h,72 h and 96 h median lethal concentration (LC₅₀) of nitazoxanide on fingerings of large yellow croaker was 6.69 mg/L, 6.45 mg/L, 5.64 mg/L and 5.04 mg/L respectively, and safe concentration was 1.69 mg/L. Nitazoxanide belongs to high toxic chemicals, but generally that of 1 mg/L in the 72-hour immersion bath can effectively remove trophozoite, therefore, the effective concentrations of insect repellent is within the range of the safe concentration and it is safe to use in production.