Knee arthroscopy is a minimally invasive surgery with little trauma and quick recovery, but it is susceptible to postoperative complications such as muscle atrophy, joint swelling, and intra-articular adhesions. Therefore, it is not clear whether knee arthroscopy will recover slowly by itself due to individual differences. However, recovery can be promoted through functional exercises. Functional exercise is a therapeutic procedure that improves lymphatic circulation, fluid and stretching of contracted tissues, loosens adhesions, prevents muscle atrophy, strengthens muscle power, prevents adhesion of soft tissues and joints, facilitates the reduction of swelling and effusion, and promotes fluid circulation in the limbs of patients. Functional exercise mainly includes three major aspects of muscle strength, joint mobility, weight bearing and walking exercises. Patients should still ask the attending physician’s opinion after knee arthroscopy to see if and how rehabilitation training is needed.