The common reasons for the swelling and pain of the foot after more than twenty days of fracture include poor stability of the fracture site, premature or excessive weight bearing of the fracture site, venous thrombosis and so on. 1. Poor stability of the fracture site: under normal circumstances, the fracture is usually fixed by manipulation, plaster external fixation or incision and internal fixation, etc. If the swelling and pain is still severe after more than twenty days, it may be due to the loosening of the plaster or the internal fixation loosening and other reasons leading to the local stability is not good. 2. Premature or excessive weight bearing on the fracture site: You can not bear weight for a period of time after the fracture of the foot, if the fracture site is prematurely or excessively burdened, for example, walking on the ground too early, it will lead to swelling and pain in the fracture site. 3. Venous thrombosis: the damage of venous lining, venous blood stagnation and other reasons may cause venous thrombosis after fracture, venous thrombosis may also cause swelling and pain in the foot. Fracture more than twenty days foot than the beginning of the swelling and pain may also be caused by other reasons, should go to the hospital in time to identify the causes and targeted treatment.