The invention relates to a parking mechanism for an automatic speed changer. The parking mechanism for the automatic speed changer comprises a ratchet wheel, a pawl, a rotating shaft, a rotating shaft bracket and a shaft sleeve; the rotating shaft bracket and the shaft sleeve are arranged on the rotating shaft in a sleeving manner; a rectangular groove is formed in the side, far away from the shaft sleeve, of the rotating shaft bracket; a slidable first sliding block is arranged in the rectangular groove; a sliding groove is formed in the side, close to the shaft sleeve, of the rotating shaft bracket; the shaft sleeve can slide along the rotating shaft under the driving of a driving device, and can be clamped into the sliding groove; the rotating shaft bracket and the shaft sleeve are used for limiting the movement of the rotating shaft in the acting force direction of the pawl. When a vehicle slides down a slope or moves, the component force, in the direction of the slope, of the gravity of the vehicle completely acts on the ratchet wheel and the pawl, and if the shaft sleeve is separated from the sliding groove at the moment, the limitation to the movement of the rotating shaft in the acting force direction can be relieved, so that the acting force between the ratchet wheel and the pawl is greatly reduced; the pawl can be separated smoothly under the action of a torsion spring; the problem that the pawl is difficult to separate caused by excessive friction force between the ratchet wheel and the pawl is solved.