OBJECTIVE： To establish a method for simultaneous determination of 3 components in Li’ermian capsule， including berberine hydrochloride， palmatine hydrochloride and cinnamaldehyde. METHODS： HPLC method was adopted. The determination was performed on Agilent Zorbax SB-C18 with mobile phase consisted of acetonitrile-0.05 mol/L potassium dihydrogen phosphate solution （23 ∶ 77， V/V） at the flow rate of 1.0 mL/min. The detection wavelengths were set at 345 nm （0-20 min， berberine hydrochloride， palmatine hydrochloride） and 290 nm （＞20-30 min， cinnamaldehyde）， and column temperature was 30 ℃. The sample size was 10 μL. RESULTS： The linear ranges of berberine hydrochloride， palmatine hydrochloride and cinnamaldehyde were 0.036 80-0.736 0， 0.016 76-0.335 2， 0.004 140-0.082 80 μg （r≥0.999 5）. The limits of detection were 0.110 4， 0.050 3，0.124 2 ng， and the limits of quantitation were 0.368 0， 0.167 6， 0.414 0 ng， respectively. RSDs of precision， stability （12 h） and reproducibility tests were all lower than 2.0％ （n＝6）. The recoveries were 96.16％-99.73％ （RSD＝0.99％-1.21％， n＝6）. CONCLUSIONS： Established method is simple， reproducible and suitable for simultaneous determination of 3 components such as berberine hydrochloride in Li’ermian capsule.