The invention provides an automatic paint spraying device for hardware processing, relates to the technical field of automatic mechanical processing, so as to solve the problems that because a workpiece has small volume and high requirement for smoothness of the paint surface, during paint spraying, once dust particles carried in the air fall on the hardware workpiece, convex particles are prone to producing, the quality of a paint film is affected, moreover, the splashed paint liquid is prone to flying to surrounding operators, and the operators are adversely affected. The automatic paint spraying device comprises a base; and a paint spraying table is horizontally and fixedly installed at the part, close to the left, of the middle of the top plane of the base. According to the automatic paint spraying device, since horizontal clamping plates are correspondingly and fixedly installed at the front end edge and the rear end edge of the paint spraying table on the top plane of the base, arack is fixedly installed on a sliding table seat at the rear side of a travel hole, a protective cover can be driven to move through the movement of the sliding table seat, thus during paint spraying, the protective cover can cover the workpiece, when paint spraying is finished, the protective cover can move to the right end with the sliding table seat, and the workpiece is conveniently taken.