T-ray coherent tomography technology(T-CT)is introduced. Compared with the X-ray computer tomography (X-CT), more information could be extracted to process the image. Theoretically, Terahertz-CT could be used to map the complex refractive index distribution in target 3 D space. Therefore, it is possible to employ the principle of Terahertz-CT to classify the target inside a black box, which implies potential applications in security inspection and nondestructive examination.