To overcome the resolution limited of large industrial CT, in this article, Micro-CT was introduced, including its concepts, principles and technological superiority. Furthermore, the advantages of Micro-CT in detection of small size aerospace materials were elaborated through examples measured by Micro-CT techniques. Indicating that Micro-CT can detect micron-level defects in materials and their distribution in space, and the size distribution of defects can be counted by image processing software, a new way for the Nondestructive Testing of Aerospace materials was provided by Micro-CT.