Breast cancer is a common malignant tumor in women and is the leading cause of female cancer death in many countries. The incidence and mortality rate of breast cancer in some industrialized countries in Europe and America are increasing year by year. Although China is a low incidence area for breast cancer, about 13,000 women die from breast cancer every year. The incidence of breast cancer has surpassed that of cervical cancer to become the first cancer among women in China. Breast cancer in men is rare, and its incidence rate is about 1% of that of women. The screening of breast cancer in North America and some industrialized countries in Western Europe is better, and many early breast cancers have been detected and cured. In China, due to the economic backwardness and low literacy level of the population, breast cancer screening is difficult and only carried out on a small scale. Therefore, breast self-examination, especially for women with high-risk factors, should pay more attention to breast self-examination and be checked once a month. It is better for amenorrheic women to fix one day a month so as not to forget. In women with normal menstruation, many normal breasts also have some nodules due to the influence of estrogen, so it is best to choose 3-4 days after menstruation is clean for examination, when the breasts are mostly loose and soft. Breast examination should be done in a brightly lit place, in a sitting or standing position, with both breasts fully exposed by removing the blouse, with both arms hanging down and looking into the mirror. 1.Visual examination: first of all, look at whether the size of bilateral breasts are similar, whether the outline is symmetrical; whether there is local bulge or depression; whether the skin of the breast is wrinkled, broken, flaking and color change; whether both nipples are on the same level; whether there is nipple depression, nipple overflow, etc. While carefully observing, both arms are raised and crossed behind the neck to observe any changes in the shape of the breast and any local skin elevation or depression. 2. Palpation: Cross your arms with your shoulders and elbows slightly forward and relax. Put down the right hand and touch the left breast with the right hand to check. Touch with the palm surface of the fingers, do not grasp and pinch the breast, touch the inner upper, outer upper, outer lower and inner lower quadrants of the breast in a clockwise direction, and finally the areola and nipple central area, be sure to feel the entire breast all over. The lump in the lower part of the breast is often covered by the sagging breast, so you can hold the breast with one hand and touch it with the other, better when you are lying down. At the same time, you should pay attention to the touch of the ipsilateral armpit, as some breast cancers have lymph node metastasis in the early stage. 3.Check the right breast by palpation. If you find abnormal breast appearance, nodules or lumps during breast self-examination, you should go to the hospital immediately for further examination. According to the statistics of the United States, about 80% of the abnormal changes found in breast self-examination are benign in nature.