Localized trauma, venous thrombosis of the lower limbs and other causes may lead to hard swelling and bruising of the calf. 1. Localized trauma: If there is a history of obvious trauma, after being hit by the outside world, there may be hard swelling and bruising of the calf. If there is no fracture, just local soft tissue contusion, it is recommended to apply cold compresses within 48 hours of the injury, and hot compresses can be applied after 48 hours. However, if accompanied by lower limb activity disorder, there is the possibility of fracture, but also need to consult a doctor in a timely manner, improve the X-ray examination of the lower limbs for further diagnosis. 2. Lower extremity venous thrombosis: If the patient has lower extremity venous or arterial thrombosis, there may be hard swelling and bruising of the calf, but also need to improve the lower extremity arterial ultrasound and other related examinations. The above are only some of the common causes. Calf belly hard swelling bruise, should seek medical attention as soon as possible. After a clear diagnosis, follow the doctor’s instructions to standardize the treatment. The use of drugs must follow the doctor’s instructions, not blindly use their own drugs, so as not to cause adverse consequences.