Abstract: Trastuzumab is a specific inhibitor against human epidermal growth factor receptor-2 (HER-2). Trastuzumab is widely used in the neo-adjuvant treatment of HER-2 breast cancer. Large-scale randomized and controlled clinical trials have demonstrated that pathologic complete response rates (pCRs) were significantly increased with neo-adjuvant trastuzumab therapy plus chemotherapy than with regular chemotherapy. The use of trastuzumab plus chemotherapy with lapatinib supplements could further improve pCR rates. Anthracycline and non-anthracycline drugs could both be used concurrently with trastuzumab. Endocrine therapy could be used as an alternative for estrogen receptor-positive patients. pCR is a powerful predictor of long-term outcomes in HER-2 positive patients under neo-adjuvant therapy with trastuzumab. However, patient loss of HER-2 expression with residual disease after neo-adjuvant therapy with trastuzumab is a poor prognostic factor. This study paper will provide a review of related research.