Breast cancer immunohistochemistry test is to guide clinical treatment and speculate the prognosis, to determine whether endocrine therapy, targeted therapy, etc. can be carried out. Breast cancer immunohistochemistry has more contents, and the ones that are more concerned about clinically are estrogen and progesterone receptors ER and PR, human epidermal growth factor-2 (HER-2), Ki67, etc. If estrogen and progesterone receptors are positive or one of them is positive, endocrine therapy can be carried out. If estrogen-progestin receptor is positive or one of them is positive, endocrine therapy can be performed; if HER-2 is positive, it suggests that targeted therapy can be used; Ki67 represents the degree of proliferation of tumor cells, and the higher the index, the higher the degree of malignancy. Breast cancer is a systemic disease, immunohistochemical examination is very important, patients should cooperate with doctors, active treatment, under the guidance of the doctor to use drugs, improve the prognosis.