Abstract: Ceramic Matrix Composite (CMC) has been widely applied for its excellent protection performance. It was hard for raditional testing means as ultrasonic to complete internal spection due to the porous structure of CMC. Terahertz Time-Domain Spectroscopy (THz-TDS) was applied to establish the THz Nondestructive Testing(NDT) model of thickness at single point and to extract optical parameters of material samples. In further verifying experiments, exploratory detection and evaluation were developed on porosity distribution and defect sizes. Scanning imaging performance and conclusion of time-frequency spectrum analysis are relatively plausible on CMC internal testing through the experiments. The study in this paper proves the revealing ability of THz-TDS on quantitative NDT and properties exploring of specific materials.