The invention belongs to the field of automatic identification of motor vehicles, and particularly relates to an automatic identifying system and an identifying method thereof for motor vehicle model classification. The automatic identifying system comprises a license plate identifying suite, a license plate identifying camera, a photoelectrical trigger, a display device, an optical curtain trigger, a laser scanner, a first server, a first exchange, a second server, an industrial personal computer, a third exchange, a second exchange and a booth charging computer. The identifying method comprises the following steps of enabling a parking lot management system to complete the identifying of the license plate in advance; after the identifying is successful, opening a gate to allow the vehicle to pass; automatically generating a serial number and providing an additional bar code of the serial number; identifying the license plate number and the vehicle contour and model parameters; according to the license plate number and approach serial number information, detecting the information of the matched vehicle; according to the license plate and serial number information, detecting the vehicle model, and storing into a background database, so as to call and query at any time. The automatic identifying system and the identifying method have the advantages that the display functions are complete, the identifying rate of the vehicle is high, the application range is wide, and the operation cost is low.