The present invention relates to the degradation and removal of organochlorine pesticides (OCP) from Chinese herb medicines. In this invention, gamma irradiation is used for the degradation and removal of OCP, such as Pentachloronitrobenzene, Aldrin, Lindane, Heptachlor, Endosulfan-1, Endosulfan-2, o,p'-DDD, p,p'-DDD, p,p'-DDE, and p,p'-DDT from Chinese herb medicines. The method of the present invention requires no chemical reagents, and the application of the method is not limited by the volume and morphology of the Chinese herb medicines.