The invention relates to a marking tool for a crossbar tip. The marking tool comprises a barrel-shaped cylinder body, a base fixedly connected with the bottom of the cylinder body, a driving device fixedly mounted on the base located in the cylinder body, an ejection head connected with the driving device and a supporting block fixedly mounted on the inner side wall of the cylinder body above the driving device, wherein an inlet for placing the crossbar tip into the cylinder body is formed in the side surface of cylinder body, an annular positioning stop rib is arranged at the top of the cylinder body inwards in the circumferential direction of the cylinder body, one part, located on one side opposite to the inlet, of the positioning stop rib is removed, a step platform is formed, and a guide inclined surface is arranged on the inner side wall of the cylinder body below the step platform; the ejection head is connected with the to-be-marked crossbar tip, and the driving device can drive the ejection head to move up and down; a sliding groove is further formed in the position, directly facing the ejection head, of the supporting block, the open direction of the sliding groove is consistent with the direction of the inlet, and the crossbar tip can slide up and down in the sliding groove.