Breast pain may be caused by breast hyperplasia, acute mastitis, and local soft tissue injury. 1. Mammary gland hyperplasia: before the menstrual period of reproductive women, the mammary gland is affected by estrogen, there will be expansion and hyperplasia phenomenon, the soft tissue of the mammary gland will be edematous, which will appear the phenomenon of pain when the chest is touched. The pain will disappear with the end of the physiological period. 2. Acute mastitis: It is common in post-partum breastfeeding women. The reason is that the milk stagnation encourages the propagation of bacteria, breast pain, local redness, swelling and heat. 3. Local soft tissue injuries: soft tissue injuries caused by crushing and impact injuries to the chest can cause pain when the chest is touched. There may be other reasons for breast pain, so it is recommended to go to the hospital for regular treatment.