Hard nodules under the incision of cesarean section may be caused by local hemorrhage of small blood vessels, liquefaction and infection of the incision, fibrous tissue hyperplasia, etc. These conditions are different and need to be analyzed specifically. 1. Localized small vessel bleeding: if the mother feels a hard nodule under the incision within a few days after caesarean section, it may be caused by localized small vessel bleeding. 2. Incision liquefaction and infection: If the hard nodule is very large and accompanied by local redness, swelling, fever and other symptoms, it may be a symptom of incision liquefaction and infection. 3. Fibrous tissue hyperplasia: If there is something hard inside the incision three months after the C-section, it may be the fibrous tissue hyperplasia of scar formation. If there are hard nodules under the incision of cesarean section, accompanied by local redness, swelling and pain, it is recommended to consult a doctor in time, under the guidance of the doctor, improve the relevant examination, clarify the cause of the disease, and symptomatic treatment.