The present invention discloses a gantry configuration for a combined mobile radiation inspection system comprising a first arm frame, a second arm frame and a third arm frame. The first, second and third arm frames define a scanning channel to allow an inspected object to pass therethrough. The gantry configuration for the combined mobile radiation inspection system further comprises a position sensing device configured to detect a position error between the first arm frame and the second arm frame; and a controller configured to control a moving speed of at least one of the first arm frame and the second arm frame based on the detected position error, so that the position error between the first arm frame and the second arm frame is equal to zero. Compared with the prior art, the present invention is advantageous at least in that an automatic deviation correction device is provided on the gantry arm frame, and thus the position error between both side arm frames can be automatically controlled to zero, so that the gantry arm frame can be effectively prevented from being subjected to a force and deforming, and the radiation detector can receive the full ray, thereby improving the imaging quality.