OBJECTIVE： To establish a method for the content determination of sinalbin in Sinapis alba decoction piece. METHODS： HPLC was performed on the column of Sepax HP-C18 with mobile phase of 50％ acetonitrile-water solution （containing 5 mmol/L tetraoctyl ammonium bromide） at a flow rate of 1.0 ml/min， detection wavelength was 227 nm， column temperature was 30 ℃， and the injection volume was 10 μl. RESULTS： The linear range of sinalbin was 0.010 1-0.202 4 mg/ml （r＝0.999 7）； RSDs of precision， stability and reproducibility tests were lower than 2％， recovery was 98.51％-104.62％ （RSD＝1.90％，n＝9）. CONCLUSIONS： The method is simple， accurate and reliable， and can be used for determination of sinalbin in Sinapis alba decoction piece.