To construct a method for detecting schisantherin A content in composite Yiganling soft capsules. RP-HPLC method was used for detecting schisantherin A content. A Phenomenex C18 column was used, and the mobile phase was methanol-water (13:7). The flow rate was 1.0 mL/min, and the detection wavelength was 250 nm. The method had good linear relationship. The average recover rate was 98%, and RSD was 1.2% (n = 6). The method is rapid, simple, and sensitivity, and has good separation efficiency. The method can be used for detecting composite Yiganling soft capsules.