The invention relates to a mechanical device for manufacturing a printing roller, in particular to an automatic imposing bench, and solves problems of splicing, centralized positioning, clamping and the like of the printing roller of the existing intaglio roller in the manufacturing process. The automatic imposing bench consists of an imposing stone and an imposing frame positioned on the upper part of the imposing stone. The automatic imposing bench has reasonable structure and design, simple and convenient operation, high automation degree, stable operation, high positioning and machining accuracy, low labor intensity, and excellent conductivity and sealing performance. At present, the automatic imposing bench used on the production line completely achieves the design aim.