Swelling of the leg one month after ACL reconstruction surgery may be due to physiological reasons, such as swelling caused by stimulation of the knee joint after surgery, which can be relieved by hot compresses. It may also be a pathologic cause, due to trauma and infection, resulting in lymphatic reflux obstruction leading to swelling, we should go to the doctor, follow the doctor’s instructions for treatment, common treatment methods include infrared irradiation therapy and pneumatic compression therapy. 1. Physiological reasons: the anterior cruciate ligament (ACL) is easy to be injured due to its shape and function, and it is normal for the joints and the surrounding soft tissues to be stimulated and swollen after the operation, especially after the rehabilitation exercise. After the rehabilitation exercise, you can carry out hot compress physiotherapy, pay more attention to rest and strengthen nutrition. 2. Pathological reasons: trauma and infection can lead to lymphatic reflux obstruction, which in turn causes leg swelling, can use infrared irradiation therapy, through infrared irradiation therapy, can promote local blood circulation, to achieve the purpose of swelling. Pneumatic compression therapy can also be used. Pneumatic compression therapy can promote the flow of blood and lymph, thus eliminating swelling. Treatment varies from person to person, and should follow the doctor’s instructions to avoid aggravating the condition.