A mobile vehicle inspection system includes a moving device; a driving device for driving the moving device to move during scanning inspection; a radiation source disposed on the moving device for emitting a ray; a rotary table pivotally disposed on the moving device; an upright post installed on the rotary table at a lower end of the upright post; traverse detector beam having an end connected with an upper end of the upright post; the upright detector beam having an upper end connected with the other end of the traverse detector beam, and extending downwards from the other end of the traverse detector beam so that the upright post, the traverse detector beam and the upright detector beam constitute a frame of a substantial inverted “U” shape, a ray emitted from the radiation source so as to inspect a vehicle to be inspected which passes through the inverted-“U”-shaped frame.