Abstract: Abnormal activation of the PI3K-Akt-mTOR signaling pathway plays an important role in the development of breast cancer. In breast cancer treatment, PI3K-Akt-mTOR signaling pathway is correlated with drug resistance of the endocrine and antihuman epidermal growth factor receptor-2 (HER-2) target therapy in breast cancer patients with hormone receptor positive or HER-2 positive. The mTOR is located downstream of the signaling pathway and is closely related to the transcription, translation, proliferation, metabolism, and metastasis of tumor cells. The mTOR inhibitors, which can restore the sensitivity of endocrine therapy, exert anticancer effects by acting on the PI3K-Akt-mTOR signaling pathway through different targets. The present paper reviews the recent progress on mTOR, mTOR inhibitor, and PI3K-Akt-mTOR signaling pathway in breast cancer , and provides a reference for relevant studies and long term clinical applications.