Abstract: In order to improve the longitudinal resolution of a terahertz coherence tomographic imaging system, the dispersion compensation method was used to solve the dispersion problem caused by the broadband light source. The iterative compensation algorithm based on the evaluation function was used to compensate the dispersion of the original signal after noise reduction, and clear 3-D reconstructed images were obtained. The results show that 3-D high precision reconstruction images can be obtained without predicting the thickness information and dispersion characteristics of the sample. The longitudinal resolution is up to 100μm. This research has great research value and wide application prospect in the field of high precision nondestructive detection.