Abstract: Both conventional radiography and micro-CT experiments are performed on the internal defects detection of Ti-6Al-4V alloy material with a thickness of 10mm manufactured by selective laser melting. According to the result, for the Ti-6Al-4V alloy component with a thickness of 10mm, the artificial defect with size (diameter×length) of φ0.5 mm×0.5 mm can be detected by conventional radiography technique, and the sensitivity of pore defect could reach 0.4 mm along the direction of 10mm, which could meet the internal quality requirement for the products. The smallest defect detected by micro-CT is 33 μm, and more than 90% of internal defects were of sizes less than 200 μm and the proportion of porosity defects larger than 33 μm is 0.005 61%. Radiography technique is mainly used for internal quality inspection of products, micro-CT technique has higher sensitivity and it can provide sufficient information for the identification and characterization of defects with different scales.