The invention relates to the technical field of treatment performed after lightweight steel structure connecting pieces are cut off, and discloses an edge and corner grinding device for the light steel structure connecting pieces. The edge and corner grinding device for the light steel structure connecting pieces comprises a device bottom box, a conveying roller is fixedly arranged at the top of the device bottom box, two open grooves are formed in the top of the device bottom box, fixing plates are arranged in the open grooves, moreover, the two fixing plates are parallel to each other, rollers are arranged on the fixing plates, a sliding rod is movably connected between the bottoms of the side surfaces of the two fixing plates, the two ends of the sliding rod penetrate through the side surfaces of the fixing plates correspondingly and are fixedly connected with the front inner wall and the rear inner wall of the device bottom box, a two-way screw is connected between the bottoms of the side surfaces of the two fixing plates in a threaded mode, one end of the two-way screw penetrates through the side surfaces of the fixing plates to be rotationally connected with the front inner wall and the rear inner wall of the device bottom box. According to the edge and corner grinding device for the light steel structure connecting pieces, the problems that after the light steel structure connecting pieces are cut off, the hand is prone to be cut and hurt during mounting, moreover, an existing device capable of performing deburring grinding is held by the hand for grinding, so that the efficiency is low, and the safety is not high are solved.