OBJECTIVE： To establish a method for simultaneous determination of ferulic acid， catalpol， emodin and emodin methylether in Yishen yansi pills. METHODS： Double wavelength HPLC method was adopted. The separation was performed on Kromasil-C18 column with mobile phase methanol-0.1％ phosphate solution （78 ∶ 22，V/V） at flow rate of 1.0 mL/min. The detection wavelengths were set at 210 nm for catalpol， 280 nm for ferulic acid， emodin and emodin methylether. The column temperature was 30 ℃， and sample size was 10 μL. RESULTS： The linear ranges were 0.090 8-2.270 0 μg/mL for ferulic acid （r＝0.999 9）， 0.199 0-4.975 0 μg/mL for catalpol （r＝0.999 3）， 0.354 0-8.850 0 μg/mL for emodin （r＝0.999 9）， 0.336 0~8.400 0 μg/mL for emodin methylether （r＝0.999 7）， respectively. The limits of quantitation were 14.66， 8.75， 10.26， 13.68 ng， and the limits of detection were 5.66， 2.67， 3.78， 4.25 ng， respectively. RSDs of precision， stability and reproducibility tests were lower than 2.0％. The recoveries were 101.15％ -102.73％（RSD＝0.58％，n＝6）， 99.20％-101.69％（RSD＝1.20％，n＝6），100.90％-101.36％（RSD＝0.16％，n＝6），95.64％-98.96％（RSD＝1.49％，n＝6）， respectively.  CONCLUSIONS： The method is accurate， reliable， simple and suitable for simultaneous determination of 4 kinds of components in Yishen yansi pills.