Abstract: This paper focuses on the fatigue performance of aluminum alloy 3D printing materials. First, the fundamental principles of the fatigue behavior of aluminum alloys are elaborated, including the mechanisms of fatigue failure and the major influencing factors such as internal defects and external stresses. Then, the influence of 3D printing on the microstructure and macroscopic properties of aluminum alloys is discussed, with particular emphasis on the role of internal defect characteristics and process parameters in fatigue performance. These include the types and distributions of defects, as well as the relationships between fatigue properties and process parameters such as laser power, scanning speed, and layer thickness. On this basis, strategies for improving fatigue performance, such as material composition optimization and process refinement, are proposed. Finally, the research is summarized, and future research directions are outlined, providing both theoretical support and practical reference for enhancing the fatigue performance of aluminum alloy 3D printing materials.