To study the chemical constituents of the alkaloid fraction of Kushen decoction.Constituents were isolated by different kinds of column chromatography and their structures were elucidated with spectral methods.Eight compounds were isolated and identified as matrine (I), sophoridine (II), sophocarpine (III), sophoramine (IV), oxymatrine (V), oxysophocarpine (VI), aloperine (VII) and sparteine (VIII).All these compounds were isolated from Kushen decoction for the first time. Aloperine was found firstly in Sophora flavescens, or Scutellaria baicalensis, or Rehmannia glutinosa which constituted Kushen decoction.