Objective To determine the content of morphine in Yinghuang Powder by HPLC. Methods The analysis was performed on a Hypersil Kromasil C 18 (150 mm×4.6 mm, 5 μm) column at room temperature with a mobile phase consisting of methyl cyanide -0.01 mol/L dibasic potassium phosphate -0.005 mol/L sodium heptanesulfonate (18∶41∶41) at a flow rate of 1 ml/min. The detection wavelength was set at 220 nm. Results Morphine showed a good linear correlation within the range 1.5~30.0 μg/ml ( r =0.9999)，The average recovery and RSD were 99.16％and 1.17％, respectively. Conclusions This method is simple, accurate and repeatable, which can be used for quality control of Yinghuan Powder.