Abstract: Metal additive manufacturing (AM) technology is widely used in aerospace and other advanced industrial fields due to the unique advantage in the rapid forming of complex metal components. However, the defects induced damage behaviors of the AM parts under different service loads and environments are different. Traditional non-destructive testing technology can not dynamically characterize the evolutions of the internal microstructure of materials in real time, while synchrotron radiation X-ray tomography (SR-CT) has many advantages in it, such as strong penetration, high spatial and three-dimensional visualization, etc. Based on the analysis of the principle and characteristics of SR-CT and taking the AM titanium alloy as an example, some typical applications of SR-CT are briefly introduced, such as the quantitative analysis of the size, morphology and distribution characteristics of defects in AM parts, the in-situ observation of defects induced fatigue damage, and the finite element simulation analysis based on three-dimensional imaging data. The broad application prospects of SR-CT based on High Energy Photo Source (HEPS) in the field of AM metal materials are prospected.