Abstract: The photolysis of matrine and total alkaloids in Sophora alopecuroides in the sunlight and the UV-light were studied. In the sunlight or UV-light, the matrine and total alkaloids in S. alopecuroides were photolysised rapidly, both of them with half-lifes of less than one hour. In order to inhibit the photolysis of matrine and total alkaloids in S.alopecuroides and enhance their photostability, eleven photostabilizers were selected as photolysis inhibitors of matrine and total alkaloids in S. alopecuroides. The result shows that all the eleven photostabilizers exhibited the effects of photolysis inhibition, especially TBHQ (Tertiary-butylhydroquinone)with the best effects of inhibition.