Objective To discusse the rule of traditional Chinese medicine in Cao Lingxian’s treatment of polycystic ovarian syndrome (PCOS) and provide a theoretical basis for the clinical treatment of PCOS，through the analysis of statistical description,association rule analysis and feature selection algorithm.Methods We selected  the data of 62 patients with PCOS treated by Cao Lingxian,including the traditional Chinese medicine data and 21 causes.The database was established in Excel and the data were subject to correlation  analysis by IBM SPSS Modeler .The rule of traditional Chinese medicine and important etiology of PCOS were obtained.Results Sixty-two patients of PCOS used a total of 14729 Chinese herbal medicine.And the use of the highest frequency of five Chinese medicine were Codonopsis,Curculigo,Angelica,Anemarrhena,madder.The analysis based on association rules showed that Pueraria and Cistanche had the highest confidence,and the support of dodder and angelica was the highest.Etiology analysis showed that breast tenderness,long menstrual period,irritability and amenorrhea were the most important factors.Conclusions The mostly related medicine pairs are Chinese Angelica-Madder Root and Anemarrhena-Puerarin,and the most important causes are breast tenderness,menstrual period long,irritability and amenorrhea,which provides a valuable treatment ideas in the clinical treatment of PCOS.