The invention relates to a printing cylinder on which a printing rubber blanket can be tensioned. The printing cylinder includes a cylinder body; a clamping channel extending in the axial direction of the cylinder body; a clamping mechanism arranged parallely to the clamping channel and used for fixing the end part of the printing rubber blank in the clamping channel, wherein the clamping channel is defined by a plurality of side faces which define one space and is capable of introducing the end part of the printing rubber blanket into the clamping channel and further into the space, the clamping mechanism includes a spindle capable of rotating and having a substantial cylinder shape, the diameter of the spindle is smaller than that of the cylinder body, the cylinder has a substantial columnar spindle accommodating chamber which is parallel to the clamping channel and supports the spindle for relative rotation, the spindle substantially occupies the spindle accommodating chamber and defines at least one side face of the clamping channel, wherein the spindle can move relative to the circumference surface of the cylinder body along the circumference direction till the spindle rotates to a closed printing rubber blanket holding position, thus the spindle completely closes the clamping channel while only the end part of the printing rubber blanket is kept in, and the spindle has a circumference part adjacent to one side face, the circumference part is provided with a radius of curvature substantially identical to that of the printing cylinder, thus when the spindle is in the closed printing rubber blanket holding position, the out circumference surface of the cylinder is substantially not disturbed due to free from vibration upon the operation of the printing cylinder. The clamping mechanism is provided with a longitudinal slot for placing the end part of the printing rubber blanket; or the spindle substantially occupies the columnar spindle accommodating chamber while any part of the spindle does not extends outward over the radius of the columnar spindle accommodating chamber.