Abstract: The AZ80 magnesium alloy wheel hubs were formed by the new expansion-reduced extrusion（ERE）process and the traditional extrusion（TE） process respectively. The high cycle fatigue performance was tested by Instron8801 fatigue testing machine at room temperature. The microstructure at each stage of the two processes was analyzed by metallographic microscope. And the fracture morphologies of the high cycle fatigue samples produced by the ERE process were observed by SEM. The results show that due to the dynamic recrystallization and high equivalent strain, the wheel spokes formed by the ERE show almost uniform equiaxed structure, with an average grain size of 11 μm, which is far lower than 28 μm of the TE process. Under the condition of stress ratio R=-1 and number of cycles 10⁷, the fatigue strength of the wheel hubs formed by ERE is 129.7 MPa, which increase 4 MPa compared with that of the TE process. The fatigue cracks of the wheel hub specimen are mainly initiated at the defects of the surface; there are a few cleavage planes, dimples and tearing edges in the crack propagation region, and fatigue glow lines appear; the transient fracture region consists of a small number of dimples and more cleavage steps.