The invention discloses a workpiece horizontal rotating device. The device comprises a driving device, a guiding strip, a rolling wheel, a tray, a rotary motor, a disc bearing, a support plate and a support frame; and the driving device and the rotary motor are arranged on the support plate, the disc bearing is arranged below the support plate, a driving shaft of the rotary motor is provided witha gear matched with the disc bearing, the driving shaft of the rotary motor penetrates through the support plate and is in meshing transmission with the disc bearing, the support frame is a middle hollow frame, the support frame is arranged above the support plate, the driving device and the rotary motor arranged on the support plate are arranged on the hollow part of the support frame, the rolling wheel is arranged on the side wall of the support frame, the guiding strip is arranged on position, above the rolling wheel, of the support frame, the tray is arranged on the guiding strip, the driving device can drive the rolling wheel to rotate, and the rolling wheel can drive the tray to move in the direction of the guiding strip. The rotary device can rotate at multiple angles, can realize the rotation of a light workpiece and a heavy workpiece and ensure the stability of the workpiece conveying and rotation.