After knee replacement surgery, muscle strength training, functional training and gait training of the knee joint should be carried out under the supervision of the doctor. Knee replacement is mainly used for patients with severe osteoarthritis of the knee to replace the diseased knee joint with an artificial one for mobility. Since the main function of the knee joint is to straighten and flex, active or passive knee straightening and flexing exercises can be performed from the second day after surgery under the guidance of the doctor. The main exercise is to lie down, actively or passively bend the knee joint, and then hold it for 3~5 seconds and then slowly return to the straight state. You can do this exercise 10-20 times per session, once an hour when you are awake. You can also sit up with your legs hanging over the edge of the bed, also knee bending exercise. In addition to these exercises, the muscles of the lower limbs should be strengthened. These rehabilitation exercises can prevent joint stiffness and venous thrombosis of the lower limbs. Gait training is also needed to restore normal walking, which can be uncomfortable when walking for the first time. It is recommended that the patient follow the doctor’s instructions for rehabilitation exercises, and that he/she should be reviewed in a timely manner, and if he/she has any discomfort, he/she should stop the exercises and seek medical attention.