The invention discloses a processing method of a fine-grain pure titanium bar. The method comprises the following steps: taking 0-grade sponge titanium, industrial pure iron and titanium dioxide as raw materials, preparing the materials according to nominal components in order to prepare TA2, carrying out vacuum self-consumption secondary remelting to prepare a TA2 cast ingot, forging and rollingthe TA2 cast ingot into a bar with size of phi15-phi30mm; successively annealing, straightening, grinding and polishing the obtained TA2 bar with size of phi15-phi30mm until a fine-grain pure titaniumbar with surface roughness of 0.8 micron is obtained. The method is used for preparing a fine-grain pure titanium bar with high punch molding performance and a range of phi15-phi30mm by adjusting thecontent of impurities in pure titanium, refining internal structure through a rolling process, properly increasing thermal treatment heat preservation time, completely eliminating stress and improving the surface quality of the bar.