Premenstrual syndrome refers to physiological and mental changes before menstruation, such as irritability, susceptibility to rage, nervousness, edema, diarrhea, headache and distending pain in the breasts without obvous organic changes in examination. This syndrome usually occurs 7-14 days before menstruation and disappears after menstruation. The incidence is 30 %- 40 %. According to the clinical symptoms, this syndrome pertains to the conceptions of headache during menstruation, fever during menstruation, body pain during menstruation, edema during menstruation, diarrhea during menstruation, dizziness during menstruation, abnormal emotional changes during menstruation and distending pain in breasts during menstruation in TCM, generally known as symptoms before and after menstruation.