Objective To determine the content of emodin in Qinhuang Houzhen Capsule and to provide evidence for its quality criteria.Method A HPLC method was established as follows: Dionex AcclaimTM120 C18 cloumn(4.6? 150 mm,5 ? m),methnol-0.4 % phosphoric acid aqueous solution(85∶ 15) as mobile phase,flow rate at 1.0 mL/min and detection wavelength at 254 nm.Results The average content of emodin in Qinhuang Houzhen Capsule was 0.2057 mg/g,and RSD=4.11 %.Conclusion The content of rhubarb calculated by emodin in 1 g Qinhuang Houzhen Capsule could be affirmed at 0.150 mg/g tentatively.The method is simple,acurate,repeatible,and can be used for the quality control of Qinhuang Houzhen Capsule.