Immunohistochemistry after pathological examination of tumors can clarify the molecular typing of tumors, and also help to identify therapeutic targets, providing a basis for determining the subsequent treatment plan. Immunohistochemistry, known as immunohistochemistry, uses immunological antigen-antibody binding reaction for detection, using antibodies with fluorescent substances combined with tumor cell surface antigens for qualitative, localization and quantitative detection of antigens. Immunohistochemistry can clarify the molecular typing of tumors, for example, breast cancer can be classified into estrogen receptor-positive, triple-negative, and HER-2 overexpression breast cancers, which can be used to target the use of endocrine drugs and targeted drugs and so on. Pathological examination of tumors is mainly used to clarify the benign or malignant nature of tumors and pathological types, while immunohistochemistry examination of the expression of certain antigens in tumor tissues can further refine the typing and provide the basis for subsequent treatment.