A permanent magnetic buffer suspension type air rail train retaining device can effectively simplify the structure and reduce the workload of maintenance and repair, thus reducing the running cost ofan air rail train railway line. The train retaining device includes a fixed support and a permanent magnetic buffer; the fixed support is fixedly installed below the walking surface of a track beam, and the permanent magnetic buffer is fixedly installed on the fixed support, the front of the permanent magnetic buffer is provided with a buffer head subjected to the action of the permanent magneticbuffer, and a guiding mechanism is arranged between the buffer head and the fixed support so as to make the buffer head to keep longitudinal movement. The permanent magnetic buffer comprises an insulating sleeve and at least two permanent magnets arranged longitudinally in the insulating sleeve at intervals, and the magnetic poles of the adjacent ends of every two adjacent two permanent magnets are the same.