In order to investigate the effect of two kinds of mandrel direct hole expansion strengthening methods, solid mandrel and split mandrel, on the fatigue properties of 7050 aluminum alloy. A three-dimensional finite element simulation model of 7050 aluminum alloy of mandrel direct hole expansion strengthening was established, direct hole expansion strengthening test of mandrel were carried out, hole wall stress and fatigue properties of no expansion strengthening and mandrel direct expansion strengthening specimens were compared and analyzed. The results show that, the difference between the maximum residual compressive stress of the hole wall before and after the ream machining of the mandrel direct hole expansion strengthening specimen is less than 20 MPa. The residual compressive stress formed in the hole wall of the specimen after the direct hole expansion strengthening of the mandrel can offset the tensile stress generated in the process of partial loading. The median fatigue life of the solid mandrel hole expansion strengthening specimen is 1.46 times that of the no expansion strengthening specimen, and the median fatigue life of the split mandrel hole expansion strengthening specimen is 1.52 times that of the no expansion strengthening specimen. The mandrel direct hole expansion process reduces the number of fatigue sources, reduces the fatigue striation spacing in the fatigue crack propagation zone, and improves the fatigue life of hole structures.