Pharmacokinetics of norfloxacin nicotinate in Songpu mirror carp（Cyprinus carpio specularis）was studied in this experiment. To integrated mere aggregation method and two-step method, fify-four Songpu mirror carp were divided into three groups randomly and oral administed of norfloxacin nicotinate in a single dose of 10, 30, 60 mg/kg, respectively. Then fish in each dose group were divided into three groups, and blood was collected at 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 12, 24, 36, 48, 72 h after administration alternately, fish were kept alive during the whole process. The concentration of norfloxacin was determined by high performance liquid chromatography (HPLC), and the pharmacokinetics of norfloxacin nicotinate in plasma of Songpu mirror carp was analysed by 3p97. The results showed that R2 approached 1 in the norfloxacin concentration range of 0.1 to 100 mg/L (Fig.2), the average recovery was ranged from 97.26% to 99.06% in different concentrations (Table 1). After a single oral administration of three doses respectively, the concentrations versus time of norfloxacin in plasma (Fig.3) were all well described by two-department open model with first-order absorption. The absorption half-lives (t1/2ka) were 0.165, 0.061, 0.043 h, respectively; the elimination half-lives (t1/2β) were 18.282, 29.969, 42.051 h, respectively; the peak times (Tmax) were 0.333, 0.327, 0.302 h, respectively; the maximum content (Cmax) were 4.780, 6.247, 12.689 mg/L, respectively; the area under concentration-time curve (AUC) were 32.698, 53.015, 174.998 mg·h/L, respectively; the apparent volume of distribution (Vd) were 1.044, 4.347, 4.561 L/kg, respectively (Table 2). The results showed that with the increase of dose, the absorption and elimination rate of norfloxacin was accelerated, the pharmacokinetic characteristics were significantly influenced by dosage.