Polycystic ovary syndrome (PCOS) is a heterogeneous disorder affecting almost4%-7% of the female population of reproductive age. Its heterogeneity is characterized by a wide spectrum of features, including ovulatory dysfunction and infertility, hyperandrogenism, hyperinsulinemia, insulin resistance (IR), and progression to type 2 diabetes.Since the Ming Dynasty in China,PCOS has been defined as "phlegm and wetness"infertility in traditional Chinese medicine ,namely "metabolic infertility".Chinese herbs have been used to treat PCOS for thousands of years with good effects.Berberine has also been used for diabetic patients in traditional Chinese medicine for hundreds of years. Recent studies have reported its effects on hyperglycemia and dyslipidemia.The purpose of this study is to determine whether Letrozole combined with berberine are effective in the treatment of infertile PCOS patients.