Abstract: Nondestructive inspection is a technique which can be conducted directly in the test field with no damage to the parts or materials, and is widely used in evaluating the quality of samples.Terahertz waves (THz) have the characteristics of low energy and, for most non-polar substances,good transmission. As a new technique, THz nondestructive inspection has become a powerful supplement for existing nondestructive inspection technology. In this paper, the basic principle of THz imaging systems is introduced, and the application of continuous THz nondestructive inspection in actual sample testing is reviewed. Experimental results show that the inner defects in various samples can be detected usingTHz techniques.