Abstract: In order to investigate the effects of drilling and reaming on the fatigue life of LY12CZ aluminum alloy specimen, a fastener hole was machined by drilling and reaming process, respectively, and fatigue tests were carried out. And the surface morphology, roughness and tangential residual stress of the hole wall were measured and analyzed as well as the fatigue fracture characteristics. The results show that the surface of hole wall after drilling was rough and its average surface roughness was 12.92 μm, while the surface of hole wall after reaming was much smooth and its average surface roughness was 1.57 μm. Moreover, the stress in the surface of hole wall after drilling was tensile residual stress and its magnitude reached to 310 MPa, while it was compressive residual stress after reaming and its magnitude reached to 78 MPa. Compared with the drilled specimen, the reamed specimen had narrower fatigue slip striation, and lower fatigue crack growth rate. The average fatigue life of the reamed specimen was 1.81 times as long as the drilling specimen.