Breast cancer is one of the tumors with the highest morbidity and mortality rate in women. The cause of breast cancer is still unclear and may be related to genetics, early age of menarche and late age of menopause. The early stage of breast cancer may be asymptomatic, but as the disease progresses, it may show local and systemic symptoms. For example, the local skin sunken like a dimple, which is called “dimple sign”; the cancer cells block the subcutaneous lymphatic vessels, which can lead to skin edema and “orange peel-like changes”; skin rupture; nipple retraction and eczema-like changes; nipple overflow; axillary lumps, etc. If breast cancer is detected and treated early, the mortality rate can be significantly reduced. However, the cause of breast cancer is still unclear, so prevention is difficult, but some early signs of breast cancer can help to detect breast cancer early. (1) Regular physical examination. This includes doctor’s palpation, ultrasound and mammogram. (2) Family history of breast cancer, early menarche (less than 12 years old), late menopause (more than 50 years old), infertility, advanced pregnancy, obesity, etc. should be taken into consideration. Breast self-care (1) Self-reflection in the mirror: First, face the mirror, raise your arms above your head and observe whether there is any change in the shape and contour of both breasts; whether there is redness, swelling and orange peel-like changes in the skin of the breasts; whether the nipples are at the same level, whether there is elevation, retraction and depression, whether there is abnormal discharge from the nipples and whether there is any change in the color of the areola. (2) Flat touch method: First, take a supine position with the right arm raised above the head and a small pillow under the right shoulder to make the right breast flat. Then put the four fingers of the left hand together and use the palm side of the fingers to check the clockwise circumferential method, that is, use the four fingers to check clockwise from outside to inside in a circular manner starting from the nipple area to see if there is a palpable mass. Regardless of whether abnormalities are found or not, it is recommended to have an annual breast specialist examination to rule out early lesions.