Tumor tissue is a complex of tumor cells, stromal cells, and extracellular matrix, and they constitute a disordered and aggressive microenvironment, which plays an indispensable role in the occurrence and development of tumors. In breast cancer, cancer-associated fibroblasts (CAF) not only promote the occurrence, proliferation, invasion, metastasis, and drug resistance of tumor, but also participate in events including angiogenesis, lymph angiogenesis, extracellular matrix remodeling, and reconstruction of the microenvironment, which are known to induce cancer. Therefore, a new strategy for tumor therapy is provided by targeting CAF. This article reviews the research progress of CAF in breast cancer.