Abstract: The (R)-lansoprazole powder for injection was dissolved in methanol to prepare a 5.00 mg·L^-1 sample solution, and chromatographic analysis was carried out under the following conditions:Chiralpak ID chiral column (4.6 mm×250 mm, 5 μm) was used as stationary phase, the column temperature was 35℃, the mobile phase was a mixture of n-hexane, isopropanol and glacial acetic acid (70+30+0.2), the flow rate was 0.6 mL·min^-1, and the diode array detector was used for detection at the wavelength of 285 nm. The results showed that, linear relationship was found between peak area and mass concentration of (S)-lansoprazole in the range of 0.48-4.81 mg·L^-1, the detection limit (3S/N) was 2.4×10^-3mg·L^-1, and the lower limit of determination (10S/N) was 4.8×10^-3mg·L^-1. Values of recovery obtained by standard addition method were in the range of 97.5%-103%, and RSDs (n=6) were less than 1.6%.