The invention relates to the technical field of a dragging system, which is especially applicable to a self-driving trailer system in radiation imaging detection and a radiation imaging detection method which utilizes the self-driving trailer system. The self-driving trailer system of the invention comprises two trailers (1, 2) with symmetrical structures; the trailer comprises a driving mechanism (5), a driving wheel group (6), a vehicle body (7), a supporting wheel device (8), a jacking oil cylinder (9), a balance wheel group (10) and a guide wheel (11); the driving mechanism, the driving wheel group and the balance wheel group are arranged on the vehicle body (7); the supporting wheel device (8) is connected with the vehicle body (7) through the jacking oil cylinder (9); the front supporting arm (8-2-4) and the rear supporting arm (8-3-4) of the supporting wheel device can tightly clamp the front wheel of the vehicle to be detected and can move up and down under the driving of the jacking oil cylinder (9). The trailer of the invention has the advantages of stable and reliable operation, simple structure, convenient application and being adaptable for the different wheel diameters of the trucks to be detected.