Abstract: The paper employed micro-CT inspection technology and image analysis methods to conduct high-resolution characterization of internal micro-defects in the selective laser melting (SLM) AlSi10Mg alloy tensile specimens. Geometric features of defects such as equivalent diameter, shortest distance to the material surface, sphericity, and surface mesh model was obtained.Simultaneously, high-resolution detection of internal damage in the failed specimens after tensile testing was conducted. The experimental results indicated that the internal defects in the tensile specimens were primarily pores and high-density inclusions, with average equivalent diameters of 30 μm and 35 μm, and average shortest distance to the material surface of 0.89 mm and 0.70 mm respectively. The average sphericity was 0.71 and 0.70. The mesh model of the pore surface structure was reconstructed with sub-voxel accuracy, and micro-cracks caused by high-density inclusions were discovered in the fracture area of the failed specimen, with an average opening width of 20 μm.