The traditional determining method (high performance liquid chromatography, HPLC) to Olaquindox was improved in this thesis, including simplifying extracting steps and changing liquid system. The improved HPLC was used to determine the Olaquindox content in fish muscle tissue and feeds. The results showed that the minimum determination limits of this method is 0.100 mg/kg, the average recovery rates and relative standard deviations were 77.6% -90.1% and 0.495 - 4.920% respectively. This method was simple, rapid, precise, stable and reliable and suitable to determine Olaquindox residues in aquatic products.