Terahertz　(THz)　waves,　whose　frequencies　range　between　microwave　and　infrared,　are　part　of　the　electromagnetic　spectrum.　A　gap　exists　in　THz　literature　because　investigating　THz　waves　is　difficult　due　to　the　weak　characteristics　of　the　waves　and　the　lack　of　suitable　THz　sources　and　detectors.　Recently,　THz　nondestructive　testing　(NDT)　technology　has　become　an　interesting　topic.　This　review　outlines　several　typical　THz　devices　and　systems　and　engineering　applications　of　THz　NDT　techniques　in　composite　materials,　thermal　barrier　coatings,　car　paint　films,　marine　protective　coatings,　and　pharmaceutical　tablet　coatings.　THz　imaging　has　higher　resolution　but　lower　penetration　than　ultrasound　imaging.　This　review　presents　the　significance　and　advantages　provided　by　the　emerging　THz　NDT　technique.　©　2018,　Higher　Education　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.