A train inspection system by imaging through radiation, having a scanning arm positioned away from the track and supported on a construction base, and vibration damping elements positioned between the scanning arm and the construction base. The system includes a detector bracket with detector arrays mounted thereon, a radiation source, a calibration device, a front collimator, and a rear collimator. The sector-shaped x-rays emitted from the radiation source penetrate through the calibration device, the front collimator, the rear collimator and the train to be inspected sequentially so as to be received by the detector arrays provided on the detector bracket.