Abstract: A tie rod fracture failure occurred when the car got off the production line. The fractured tie rod was analyzed by using scanning electron microscope, spectrometer, hardness tester and other equipments, and two-dimensional finite element numerical calculation method was used to simulate the crack formation process in the center of the rod during cold extrusion. The results show that the failure tie rod was subjected to excessive load during the cold extrusion deformation process, which resulted in multiple internal cracking, so the effective linked area was greatly reduced. Therefore, the tie rod fractured when the car moved.