Postoperative functional rehabilitation exercises are the key to successful knee replacement surgery. The principle is to start early and progress gradually, combining passive and active, isometric and isotonic, but in a painless manner. The affected limb is elevated after surgery to eliminate swelling. The joints at the end of the limb should be exercised for movement, and several times on the day of surgery and on the 1st postoperative day. The muscles should be exercised on the 1st postoperative day by performing isometric contractions, which should be performed several times a day for 15 to 20 minutes each time, making a hundred contractions. These exercises are very important in the early recovery. As the muscle contraction of the affected limb can promote the venous and lymphatic return of the limb, which not only reduces the risk of deep vein thrombosis, but also reduces the adhesions and contractures of intra-articular adhesions and extra-articular muscles, eliminates swelling, facilitates the prevention and treatment of joint mobility disorders, and promotes the functional recovery in the future. Passive exercise was performed on the CPM machine from the 2nd day after surgery. The angle starts from 0 to 50°, and the exercise is continued for 1 hour, twice a day. The angle was increased by 5 to 10° day by day, twice daily. The knee was flexed beyond 90° within 2 weeks after surgery. If pain is severe or there is subcutaneous stasis, the degree should be reduced appropriately and analgesia should be provided. It is common to see that the active movement angle of the limb after shutdown is less than the onboard movement angle, which is due to the weak active muscle activity. Therefore, in the passive exercise of CPM, patients should do active exercise as follows: ①Patients take the supine position, support the bed with both hands, straighten the knee joint to lift the limb off the bed, alternate the lower limbs, and perform the exercise of the quadriceps. ②The lower limbs are straightened, and the muscles of the lower limbs are contracted for several seconds and then relaxed to exercise the muscle stretching and contraction function of the lower limbs. ③Patients sit on the edge of the bed with the lower leg down and slowly flex and extend the knee joint; in the supine position, slowly flex and extend the knee and hip joints. After the patient can get up and walk, the main purpose is to strengthen the muscle strength, expand the joint mobility and increase the amount of movement. The patient can be assisted by two people to get out of bed and stand, with the weight on the healthy side for 10 seconds, and then shift the weight to the affected limb for 10 seconds, and after resting for a while, the patient can be helped to walk about 10 steps in the hospital room without dizziness. The patient can also try to get out of bed with the help of crutches, but the crutches should bear 50% of the weight. After discharge from the hospital, the patient should continue functional exercises to enhance joint mobility and maximize the recovery of life functions.