The gear rack marking machine comprises a hydraulic rod, a conveying belt, supporting plates, a V-shaped groove, a feeding pipe, a marking device and a discharging pipe, the telescopic end of the hydraulic rod is horizontally and linearly arranged rightwards, the conveying belt is arranged on the right side of the hydraulic rod, the rotating path of the conveying belt is perpendicular to the hydraulic rod, and the multiple supporting plates are arranged on the belt face of the outer side of the conveying belt; the upper end face of each supporting plate is provided with a V-shaped groove linearly formed in the left-right direction, the V-shaped grooves penetrate through the left end face and the right end face of the supporting plate, the V-shaped grooves are matched with the hydraulic rods, the right side of the conveying belt is provided with a feeding pipe, the feeding pipe is coaxial with the telescopic ends of the right sides of the hydraulic rods, the feeding pipe is matched with the V-shaped grooves, and the right end of the feeding pipe is provided with a matched marking device. The right side of the marking device is provided with a corresponding discharging pipe. According to the marking device, automation of marking of the threaded rod can be achieved, the manpower requirement is lowered, and the production efficiency is improved.