Abstract: OBJECTIVE To study the transformation between oxymatrine and matrine, oxysophocarpine and sophocarpine in the extraction process of Sophora alopecuroides. METHODS Different extraction solvent (water and 55% ethanol), pH and extraction time were used to study the transformation rule of oxymatrine and matrine, oxysophocarpine and sophocarpine in Sophora alopecuroides Semen and Sophora alopecuroides herba by HPLC. RESULTS With the increasing of extraction time, the amount of oxidized alkaloids transformed into reduced alkaloids increased; extraction solvent made no difference in the effect of the transformation of Sophora alopecuroides alkaloids; with the increasing of extraction time, the additive amount of oxymatrine and matrine decreased slowly, the additive amount of oxysophocarpine and sophocarpine also decreased slowly. CONCLUSION The results provide a basis for quality control of alkaloids of Sophora alopecuroides, also can provide a basis for industrial extraction of Sophora alopecuroides.