The incidence of breast cancer in China has ranked first among female malignant tumors. The actual incidence rate is as high as 53/100,000 per year. Breast cancer has become a threat to women’s health and a “red-faced killer”. The earlier breast cancer is detected, the greater the chance of cure. If you find any abnormalities, you should go to a specialized hospital for further professional examination once a month for breast self-examination so that early detection, early diagnosis and early treatment can be achieved. The best time for breast cancer self-examination is one week after menstruation, because before or during menstruation, due to physiological congestion of breast, tissue changes such as glandular follicle hyperplasia and ductal expansion, which make breast tissue hypertrophy, affect the examination effect. If the menstrual cycle is irregular, it is best to perform self-examination at the same time of the month. Once abnormalities are found, go to the hospital for further investigation in time. 1, visual inspection upright mirror before taking off the top, in bright light, facing the mirror on both sides of the breast for visual inspection, compare bilateral breast symmetry, pay attention to the shape of the size and abnormal changes. The abnormal signs mainly include: nipple overflow, nipple retraction, skin wrinkling, dimple sign, skin flaking and abnormal changes in the appearance of the breast contour. 2. Lift the left upper limb and use the three fingers of the right hand (index finger, middle finger, ring finger) to touch the breast slowly, steadily, and carefully, moving gradually in the left breast in a cis or trans direction, at least three circles from the periphery of the breast to the nipple. The breast may also be examined in an up-and-down or radial direction, but care should be taken not to miss any part. The axillary lymph nodes are also checked for enlargement. Finally, the nipple is gently squeezed between the thumb and index finger to observe for nipple drainage. If you find cloudy, yellowish or bloody fluid, you should seek medical attention immediately. 3, lying down check lying down check, to be tested upper limbs raised over the head on a pillow or with a folded towel pad to be tested under the shoulder. The purpose of this position is to make the breast flat and easy to check, and the method is the same as that of palpation.