The invention relates to an auto pillow bolt locking device, and belongs to the technical field of auto assembly tools. The auto pillow bolt locking device mainly comprises a sliding table, a bolt locking gun, a stretchable carbon arm, a sliding device, a sleeve and a sliding way; according to the auto pillow bolt locking device, the bolt locking gun is suspended on the stretchable carbon arm; meanwhile, a gun head is limited through the sleeve; in addition, the bolt locking gun can move along the annular sliding way on the four side walls of a square opening under the sliding effect of the sliding device, it is guaranteed that the bolt locking gun lock bolts on an auto pillow at the four corners of the annular sliding way, the problems that exhaustion is caused by work due to manual handholding of the bolt locking gun, and the working efficiency is low are solved. As stretchable limiting devices are arranged at the four corners of the annular sliding way, the bolt locking gun cannot swing along the annular sliding way when screws are screwed, the condition that the gun body hits the wrist is avoided, and safety of operators is guaranteed.