The present invention discloses a vehicular radiation inspection system comprising a mobile vehicle body, a detection arm, a radiation source and a detector. The vehicular radiation inspection system further comprises a following mechanism separated from the detection arm. The following mechanism contains radiation protection material, and the following mechanism follows the detection arm to move in a non-contact manner during inspection of the inspected object, so as to prevent radiation leakage. In the present invention, it does not need to infuse radiation protection material having a high density, such as lead, into the detection arm. Therefore, it can effectively decrease the weight of the detection arm, and it does not need to provide a balance counterweight on the mobile vehicle body on which the detection arm is carried, thereby effectively solving the problem that the vehicular radiation inspection system has an excessively large mass. Meanwhile, in the present invention, the moving process of the following mechanism is accurately controlled, so as to prevent the following mechanism from hitting the detection arm.