In order to study the metabolism and elimination of norfloxacin (NFLX) in Pseudosciaena polyactis, single oral administration(10 mg/kg b.w) of NFLX has been investigated in healthy Pseudosciaena polyactis at (22±2) ℃. The medicine was extracted by methanol from plasma and perchloric acid (6%) from tissues. NFLX was determined by high performance liquid chromatography(HPLC). The mobile phase was methanol, 0.05 mol/L phosphate buffer and 0.05 mol/L terabutyl ammonium bromide (24.5/73.5/2, V/V/V) adjusted to pH 2.0 with phosphoric acid. The ZORAX SBC18 column was used and ultraviolet detector was 280 nm. The mean recoveries were all higher than 88.73％ for samples and interday CV for plasma and tissues were all under 9.75 %. The sensitivity was 0.01 μg/mL. The result demonstrated: Plasma concentrationtime data of NFLX were best fitted using a twocompartmental open model, absorption and distribution were fast but elimination was slow, with absorption, distribution and elimination halflife of 0.703 0, 2.092 6 and 154.326 5 h, respectively. The maximal plasma concentration was 0.886 4 μg/mL, peaking at 2.091 4 h after dosing. Area under the plasma drug concentrationtime curve from 0 to ∞ was 97.803 8 μg/h·mL. The concentration of NFLX was higher than other tisssues and all tissues’ concentration is higher than plasma at the same time. The speed from fast to slow is kidney, liver, muscle with elimination halflife of 135.88,173.25,223.55 h, respectively. As an edible tissue, muscle had a slowest depletion, so muscle was selected as target tissue in this experiment. According to the maximum residue limit(MRL) of 50 μg/kg in muscle, the withdrawl period should not be less than 23 d under this experiment condition; then the scheme of NFLX is established to fish bacterial disease, that is，the dose orally is l0 mg/kg, at the intervals of 24 h for 2～3 times．This study had theory value to application of norfloxacin (NFLX) to disease prevention and cure for aquatic animals and consumer’s health safety.