The invention relates to a folding mechanism, a car coupler and a railway vehicle. The folding mechanism includes a first rotating piece, a second rotating piece and a locking unit, the first rotatingpiece is provided with a locking groove, the locking groove is formed in one end of the first rotating piece, one end of the second rotating piece is hinged to one end of the first rotating piece, the locking unit is fixed to the second rotating piece, the locking unit includes the first locking piece and a first elastic piece, the first locking piece is hinged to the second rotating piece, the first locking piece is connected with the locking groove in a matched mode, one end of the first elastic piece is fixed to the second rotating piece, and the other end of the first elastic piece is fixedly connected with the first locking piece, wherein when the first locking piece overcomes the elasticity of the first elastic piece to rotate and is separated from the locking groove, relative rotation between the first rotating piece and the second rotating piece is unlocked. In addition, the railway vehicle includes the car coupler, and the car coupler includes the folding mechanism. Accordingto the folding mechanism, the car coupler and the railway vehicle, during coupling of the car coupler, the efficiency of adjusting a car coupler buffer and a coupling device is improved.