Abstract: Thyroid cancer and breast cancer are two of the most common malignant tumors in women. Concurrent tumors of the thyroid and breast are relatively rare in clinical practice; however, the incidence of such dual malignancies has recently increased. Researches conducted in the past mainly focused on the possible increase in the incidence of contralateral breast cancer, while the increased risk of synchronized thyroid cancer in women with breast cancer has attracted widespread attention recently. The specific mechanism has not been fully understood. This article reviews the pathogenic factors between these two diseases, and evaluates the etiological role of these factors in these double primary cancers, so as to provide a better basis for clinical practice.