X-ray computed tomography (CT) is a non-destructive approach to verify internal features of various industrial components built by additive manufacturing (AM) or other processing methods. However, the measurement results was highly impacted by numerous factors. In this study, DoE (Design of Experiments) was conducted to statistically study impacts of error source of X-ray CT metrology; optimal settings were recommended for different internal geometrical features. Measurement comparison between X-ray CT and CMM (Coordinate Measuring Machine) is also provided in this paper to analyze the principle difference of these two measurement technology.