Abstract: RP-HPLC was applied to the determination of amoxicillin in its drugs. Conditions and parameters of the method and instrument were studied and optimized. The Shim-Pack VP-ODS column (150 mm×4.6 mm,i.d. 5 μm) was used as the chromatographic column,and a mixed solution composed of the phosphate buffer (pH 5.0) and ethanol in the ratio of 90 to 10 (by volume) was used as the mobile phase. Flow-rate of the mobile phase was 1.0 mL·min-1. UV-detection at 228 nm was adopted. Linear relationship between the peak area (mV·s) and concentration of amoxidillin (g·L-1) was obtained in the range of 0.045-0.60 g·L-1 (r=0.997 4). In its application to the analysis of amoxicillin capsules,RSD′s calculated were <0.6%. Results of recovery test performed by the standard addition method were in the range of 94.7%-101.3%.