Pain when pressing on the outer ring of the breast can be caused by physiological pain due to hormone level changes or pathologic factors such as breast hyperplasia, mastitis and breast cancer. 1. Hormone level changes: when women are in pre-menstrual period, pubertal development or pregnancy, due to the increase of hormone level can cause breast pressure pain. This is a normal physiological phenomenon. 2. Mammary gland hyperplasia: Hormonal imbalance, psychological and other factors can cause breast hyperplasia, which can be manifested as pain when pressing on the breast. 3. Mastitis: In breastfeeding women, acute or chronic inflammation can be triggered by milk stagnation and infection, resulting in pain on the affected side of the breast when pressed, often accompanied by redness, swelling, fever and other manifestations. 4. Breast cancer: When breast cancer foci grow in the outer part of the breast, pain on pressure may also occur in the middle or late stage. The pain of pressing on the outer circle of the breast should also be considered as extra-mammary diseases such as lung diseases, cardiothoracic diseases, etc. If the pain of pressing on the outer part of the breast is caused by pathologic factors, it should be consulted as soon as possible to make a clear diagnosis.