Abstract: To address the unclear mechanisms of material flow characteristics and metallurgical defect formation in cold rolling of titanium alloy threads, a numerical model for cold rolling process of titanium alloy thread was established. By combining experimental and numerical simulation methods, the material flow behavior during thread rolling was clarified, and the formation mechanism of metallurgical defects at the threaded tooth side was revealed. The results show that the validity of the model is verified by comparing the simulated strain distribution with the experimental microhardness data. The strain hardening effect induced by plastic deformation significantly influences grain refinement in the thread subsurface layer, with the highest hardening degree at the thread root, followed by the thread side, and the least at the thread top. The cracks in the area above the middle diameter of the thread side are caused by dynamic stress concentration by the multi-directional flow of the material. When the local stress exceeds the material fracture threshold, the crack at the thread side is formed.