Mirror therapy is a rehabilitation therapy in which a mirror is placed between the arms or legs so that the image of a moving non-affected limb gives the illusion of normal movement in the affected limb. As a simple, safe, and low-cost treatment, mirror therapy has been widely used. By summarizing and analyzing the literature about mirror therapy at home and abroad, this article summarizes its mechanism and clinical application in pain, stroke, cerebral palsy and so on, so as to provide reference for research and application on mirror therapy.