Breast cancer is one of the common tumors in women and occupies the second place of malignant tumors in women. The early symptoms of breast cancer include breast lumps, breast skin changes, breast contour changes, nipple overflow, nipple changes, and enlarged axillary lymph nodes. Breast cancer is a superficial tumor, which is easy to detect and can be treated early to get better results. Female comrades, especially women over 30 years old, should conduct regular self-examinations to help early diagnosis and treatment of breast cancer. The steps of breast self-examination include: (1) Untie the underwear, face the mirror, relax with both hands hanging down naturally, and carefully observe the bilateral breasts, paying attention to the size, shape, contour, symmetry, whether there is bulge, swelling, depression or “orange peel sign” (i.e. orange peel-like change in the appearance of breast skin), whether there is overflow and retraction of nipples, and whether there is eczema in the areola. (2) Both arms are high. (2) Raise both arms above the head to see if there are irregular depressions and protrusions in the shape of the breast. (3) Lie on your back with a thin pillow under your shoulder blade, raise your left arm above your head and try to relax your muscles so that your left breast is completely flat on your chest wall. Care should be taken not to grab or pinch the breast with the fingers during the examination, otherwise it is easy to mistake the normal breast tissue that is grabbed and pinched for a breast lump. (4) Put your left arm down and use your right hand to press and feel the left armpit again for lumps. The right side is checked in the same way. This can be done once a month, preferably a week after menstruation, when the breasts are at their loosest and easy to examine. If you find any suspicious conditions such as lumps, you should go to the hospital and ask your doctor for further consultation.