Abstract: Endocrine therapy is most effective adjuvant treatment for estrogen receptor（ER） positive breast cancer， significantly improving disease free survival and overall survival. However， endocrine treatment failure due to drug resistance leads to poor prognosis in some patients. Recently， microRNA（miRNA） is becoming a hotspot in the field of cancer research. More and more studies demonstrated that the expression and regulation of various miRNA was one of the key factors of drug resistance mechanisms of breast cancer. MiRNA stimulated epithelialmesenchymal transition and cancer stem cells formation by modulating drug efflux transporters， antiapoptotic protein and multidrug resistance signal transduction networks. Recent studies found that miRNA could control endocrine resistance mainly by regulating ERα expression， tyrosine kinase receptor signal transduction， survival signaling and apoptosis pathway. Many studies showed that miRNA might be prognostic factor for hormone receptor positive breast cancer and predict factor for assessing the efficacy of endocrine therapy. As a new molecular marker， it is possible that miRNA can provide a new target to overcome endocrine therapy resistance so as to further improve endocrine therapy efficient of breast cancer.