Provided is a back guide rail mechanism applied to a sleeper-changing vehicle used for a track. The middle part of the top surface of a support plate is welded with a seat plate. The back side of thebottom surface of the seat plate is welded with a vertical baffle plate. A vertical back rack plate is connected with the support plate through left and right back extending plates. A tilt adjustmentoil cylinder can control angles of inclination of the support plate. The back side surface of the support plate is fastened with left and right transverse square steel sleeves through screws. The middle part of the back side surface of the support plate is welded with three limiting rods. A rectangular limiting hole is drilled in the middle part of a drifting board which is attached to the back side surface of the support plate. The vertical baffle plate is disposed behind the floating board. The bottom of the floating board is fastened with a wheel shaft through welding in order to form a left and right drifting mechanism. Left and right shaft ends of the wheel shaft are both in sleeve joint with back track wheels through bearings. The back guide rail mechanism applied to the sleeper-changing vehicle used for the track is featured by being novel in structure, high in operation and guide stability and greater in practicality.