The invention discloses a double-platform cross-printing mechanism. The double-platform cross-printing mechanism mainly is composed of a rack, a printing upper platform device, a printing lower platform device, servo motors, a coupling, ball screws, screw nut seats, linear guide rails, photoelectric switches and a running platform limiting buffer ring, wherein a lower platform has a lifting function, and automatically lifts when the lower platform is operated to a printing position and a material taking and placing position, an upper platform does not have a lifting function, and only has a left-right moving function, the lower portions of the platforms are supported by bridge type parts, and the lower platform is conveniently crossed through the upper platform. Each printing platform of the double-printing platform is provided with a UVW automatic alignment device, and the system automatically controls fine-tuning alignment when a placing material exists an error; and a lifting mechanism of the platform is used as output power through the servo motors and a right-angle speed reducer, eight groups of the linear guide rails and a plurality of sliding blocks are arranged on the fourside walls of the printing platform devices so as to achieve the smooth reciprocating motion and the guiding effect, and the printing platform achieves the purpose of accurate and stable lifting underthe transmission of the ball screws and the ball screw nut seats.