The invention discloses a travelling mechanism of a track inspection robot. The travelling mechanism comprises a track and a driving mechanism, the driving mechanism moves along the track, and the inspection robot is installed on the driving mechanism; the track comprises an aluminum profile and a chain which is arranged under the aluminum profile in parallel; the driving mechanism comprises suspension arms, a cross beam, a steady wheel set, a chain wheel, a driving motor and a steering device, a U-shaped structure is formed by the two suspension arms and the cross beam, the suspension arms make slideable contact with the aluminum profile through the steady wheel set, the chain wheel is horizontally arranged and rotationally connected with the cross beam, the chain wheel meshes with the chain, a torque input shaft of the chain is fixedly connected with a torque output shaft of the driving motor through a transmission belt, and the driving motor is fixedly connected with the cross beam.In the travelling mechanism, the standard industrial aluminum profile is used as the track, the chain is used as a path, the chain wheel is used as a driving wheel, and a chain-drive mode is adoptedso that precise positioning can be achieved, and turning and climbing can be easily achieved; the steering shaft is adopted as a steering knuckle so that the requirements for small-radius turning canbe met.