A coupler buffer for a railway vehicle. The coupler buffer comprises a mounting base (1), at least two energy-absorbing components (2), a draw bar (3), locking members (4), a rotating shaft barrel (5) mounted in a mounting hole (1-1) of the mounting base (1), a guide block (7), and snap components (6). The guide block is fixed to the mounting base by means of the axially disposed snap components to limit the axial movement of the rotating shaft barrel in the mounting hole. The rotating shaft barrel is provided with a partition (5-3) approximately perpendicular to the axial direction. The draw bar movably and axially passes through a partition hole (5-3-1) of the partition. Two sides of the partition are each provided with at least one energy-absorbing component that is sleeved on the draw bar and locked by the locking members. The mounting base is provided with a guide groove (1-2), and the guide block is at least partially disposed in the guide groove. When the coupler buffer is overloaded, the snap components are snapped approximately in the axial direction, and the draw bar drives the rotating shaft barrel to be guided by the guide block and move in the guide groove. The coupler buffer has a simple overload detachment structure, is not offset or stuck during the detachment, and is simple and compact in overall structure.