A vehicle mobile checking system includes a mobile device, a drive device which drives the mobile device to move in the period of scanning and checking, a radial source which is used to emit the radial, a rotary platform which can be rotatablely arranged on the mobile device, a column which is arranged on the rotary platform, a transverse detector beam which is connected with the upper end of the column and which is provided with a detector array, and a vertical detector beam which is connected with the transverse detector beam and is vertical to the transverse detector beam by and large and is provided with the detector array; the column, the transverse detector beam and the vertical detector beam form a 'Pi'-shaped frame; wherein the transverse detector beam and the vertical detector beam can be swung between a retraction device which can be retracted on the upper part of the mobile device and an protruding device which can be protruded out of the mobile device. The vertical detector beam of the mobile vehicle checking system of the utility model is not needed to be folded when driving period or scanning and checking period, and has the features of simple structure, convenient processing and adjustment, wide scanning range, light vehicle weight and low manufacturing cost.