In order to study the high-cycle fatigue properties of AlSi7Mg alloy fabricated by selective laser melting (SLM), the static tensile test and fatigue test under different stress loadings were performed on the as-built specimens. The microstructure and fatigue fracture morphology of the as-built specimens were observed by metallographic microscope and electron microscope, and the fatigue failure mechanisms were investigated. The results show that the tensile properties of SLM AlSi7Mg specimens are significantly higher than those of cast AlSi7Mg, and the tensile strength and yield strength are lower than those of SLM AlSi10Mg, but their fatigue limits are similar. Compared with traditional manufacturing method, the microstructure of the specimens is divided into three regions, namely the fine zone, coarse zone, and heat-affected zone. The Si phase is uniformly embedded in α-Al matrix in a network structure. Through fracture morphology analysis, it is found that the fatigue cracks of SLM AlSi7Mg specimens are initiated at the defects such as pores and inclusion, and propagate radially in a semicircle manner. When the remaining section cannot bear the fatigue load, the samples fracture instantaneously, and the fracture zone has the morphology characteristics of cleavage surface and dimple. Comparing the as-built specimens of SLM AlSi7Mg and SLM AlSi10Mg, it is found that the macroscopic differences between the tensile properties and fatigue properties of the two specimens are currently small. The microstructure of specimens formed by SLM is similar and contains a large number of scattered defects.