The invention relates to an automatic tire marking device. The automatic tire marking device comprises a conveying table and a plurality of marking mechanisms arranged on the conveying table at equalintervals, each marking mechanism comprises a support, an anti-collision fixing assembly and a large-character ink-jet printer, a sliding rail is arranged on each support, a sliding block which horizontally slides along the corresponding sliding rail is arranged on each sliding rail, each sliding block is connected with a stepping motor through a tooth-shaped belt assembly, one side of each anti-collision fixing assembly is longitudinally and rotationally connected with the corresponding sliding block, the other side of each anti-collision fixing assembly is provided with an air cylinder whichslides vertically relative to the corresponding anti-collision fixing assembly, each large-character ink-jet printer comprises a large-character spray head and an ink supply device, the large-character spray heads are connected with the ink supply devices, the large-character spray heads are located above the conveying table and are fixed to the output ends of the air cylinders. According to theautomatic tire marking device, marking process intelligent manufacturing in the tire industry is realized, the marking beauty is improved, return rubber generated in the tire production pressing-out link is reduced, the energy consumption is reduced, the graded product rate is increased, the waste of the coating is reduced, the cost expenditure of easily damaged parts is reduced, the production efficiency is improved, the labor intensity is reduced, and the quality accidents are reduced.