The additive manufacturing of AlSi10Mg alloy has broad applications in the production of complex structural components. With increasingly stringent service conditions for such parts, there is a growing demand for materials with enhanced fatigue performance. This study focuses on the fatigue performance of laser-selective zone-melted AlSi10Mg alloy. The fatigue life and fracture morphology of specimens under different forming directions and stress conditions are examined. In addition, the generation and propagation behavior of fatigue cracks are analyzed. The results indicate that fatigue cracks are often initiated by inclusions and tend to concentrate on or near the surface of the specimens. Increasing the maximum stress decreases the fatigue life. Further, specimens formed along the X/Y direction exhibit slightly higher fatigue life compared to those along the Z direction. Furthermore, increasing the stress concentration factor leads to a higher number of fatigue sources. Cracks often originate at the root of notches in stress concentration areas, propagating outward toward the instantaneous fracture zone.