Abstract: OBJECTIVE To develop a high-performance liquid chromatography for determination of ferulic acid(FA) in rats plasma which were treated with Kangmaixin oral liquid(KMX) and to study the pharmacokinetics of FA in rats. METHODS Plasma sample were extracted by liquid-liquid extraction with ethylacetate. Diamonsil TM C₁₈(4.6 mm×250 mm, 5 μm) chromatographic column and Agilent C₁₈ pre-column was used with 35 ℃ column temperature. The mobile phase consisted of acetonitrile and 0.085% phosphoric acid (17∶83). The flow rate was 1.0 mL·min^-1. The detection wavelength was set at 316 nm. The plasma concentration of FA in rat plasma after i.g. KMX was determined. The plasma concentration-time curve of FA was plotted, the compartment model was fitted and the pharmacokinetic parameters were calculated. RESULTS The assay showed good linear correlation over the range of 0.137 04-5.710 μg·mL^-1(r=0.999 8). The minimum quantity limit of FA was 6.852 ng. The sample solution was stable within 36 h. The coefficient variation of precision was <5.0%. The average recovery rate of this method was 91.8%-100.5%. FA in rats fit to two-compartment model with T_max=20.10 min, C_max=743.6 ng·mL^-1, T_l/2Ka=6.781 min, T_l/2α=17.82 min, T_1/2β=179.4 min. CONCLUSION The method is simple, sensitive and suitable for pharmacokinetics of FA, and FA can be absorbed and distributed very rapidly while the elimination is very slow after taken KMX.