A limiting mechanism is provided, including: a base; a first bearing; a turntable; and a limiting assembly. The base includes a base body and a through hole passing through the base body and having a circle shape. The first bearing is mounted in the through hole and forming a fixing connection with the base body. The turntable includes a turntable body and a shifting lever. The shifting lever rotates to the limiting portion until the limiting portion is pressed against and the limiting portion is driven to move, so that the limiting portion abuts against the limiting surface on the corresponding side to realize limiting. The limiting mechanism not only has fewer actions and has a simple structure, but also occupies a small space, has high reliability, and can reduce generation of noise.