Abstract: Fracture failure of an H13 steel extrusion rod for aluminum section occurred during normal operation, the causes of fracture failure were analyzed by means of chemical composition analysis, fracture macro and micro analysis, metallographic examination and hardness test. The results show that the transition arc between the extruded rod body and the rod seat was mistakenly processed into the run-out groove and formed stress concenfration. The extrusion rod was not fully tempered, and had high residual internal stress. The microstructure of the extruded rod was unstable, and the structure stress and anisotropy were produced in the segregation structure, which caused cracks in the edge of the run-out groove. Under the installation eccentric load, the bending fatigue fracture of the extruded rod occured in the initial stage of service.