A bullet train gauge-changing bogie for a railway vehicle, comprising a frame, the frame comprising a pair of side beams disposed in parallel and a pair of cross beams connected between the two side beams, wherein a gauge-changing wheelset is respectively disposed at exterior sides of the pair of the cross beams, the wheels of the gauge-changing wheelset are mounted with wheel-mounted brake discs; each of the side beams or each of the cross beams is mounted with a mounting seat and a brake clamp, and the brake clamp is connected with the mounting seat by support pins; the support pins are horizontally disposed below the mounting seat, and both ends thereof are fixedly connected with the mounting seat, one end of the brake clamp is provided with a connecting sleeve; the connecting sleeve is firmly sleeved with damping inner sleeves with elastic damping; the connecting sleeve is locked on the support pins through the damping inner sleeves; when the gauge is changing, the wheel-mounted brake disc on the wheel exerts a thrust on the brake clamp; when the thrust on the connecting sleeve is greater than the damping force between the connecting sleeve and the support pins, the connecting sleeve drives the brake clamp to move along the support pins, wherein the gauge-changing wheelset includes an axle, wheels and locking mechanisms; characterized in that both ends of the pairs of side beams are respectively provided with an axle-box body, wherein both ends of the axle extend into an axle-box body, respectively, and the wheels are installed on the axle and connected with the axles through splines; in that the locking mechanisms are respectively provided on exterior sides of the wheels and located in an axle-box body at both ends of the axle; and the locking mechanisms are connected with the wheels, and configured to lock and unlock the wheels to change a gauge of the wheels. a gauge-changing wheelset is respectively disposed at exterior sides of the pair of the cross beams, the wheels of the gauge-changing wheelset are mounted with wheel-mounted brake discs; each of the side beams or each of the cross beams is mounted with a mounting seat and a brake clamp, and the brake clamp is connected with the mounting seat by support pins; the support pins are horizontally disposed below the mounting seat, and both ends thereof are fixedly connected with the mounting seat, one end of the brake clamp is provided with a connecting sleeve; the connecting sleeve is firmly sleeved with damping inner sleeves with elastic damping; the connecting sleeve is locked on the support pins through the damping inner sleeves; when the gauge is changing, the wheel-mounted brake disc on the wheel exerts a thrust on the brake clamp; when the thrust on the connecting sleeve is greater than the damping force between the connecting sleeve and the support pins, the connecting sleeve drives the brake clamp to move along the support pins, wherein the gauge-changing wheelset includes an axle, wheels and locking mechanisms; characterized in that both ends of the pairs of side beams are respectively provided with an axle-box body, wherein both ends of the axle extend into an axle-box body, respectively, and the wheels are installed on the axle and connected with the axles through splines; in that the locking mechanisms are respectively provided on exterior sides of the wheels and located in an axle-box body at both ends of the axle; and the locking mechanisms are connected with the wheels, and configured to lock and unlock the wheels to change a gauge of the wheels.