Breast self-examination is the examination of one’s own breasts by the patient himself/herself, and the period of examination is 3 to 7 days after the menstrual period is cleared. The methods of breast self-examination mainly include pre-mirror examination, standing or sitting examination, lying on the back and so on. 1. Examination in front of the mirror: stand naked in front of the mirror and relax your upper limbs naturally. First, observe whether both breasts are symmetrical and of the same size. Secondly, observe whether there are rashes, abnormal bumps or depressions, ulceration and deformation of the breast skin. Finally, observe whether the nipple is inverted, overflowing or eroded. 2. Standing or sitting examination: after taking a bath or cleaning the breast, stand or sit up and lift the left hand over the head, use the index or middle finger of the right hand to examine the breast in a clockwise direction, touching whether there is any lump according to the order of outer upper, outer lower, inner upper and inner lower. After checking the left breast, follow the same method to check the right breast. 3. Lying on the back: after lying on the back, the breasts can be completely spread out, and in the order from outside to inside, from top to bottom, from the root of the breast to the nipple with the fingertips in a circle, feel the changes in the skin and the deep breast tissue. And the use of finger fingertips to touch the armpit, to see if you can feel the lymph nodes. In short, women’s regular breast self-examination is very important, if you find the breast skin abnormalities or lumps, you should go to the hospital in time for diagnosis.