Thermal barrier coating represents a pivotal technology in the enhancement of hot-end components manufacturing for aircraft engines. During the service process, alterations in the coating’s material and structure not only impact engine performance but also affect engine safety. Consequently, the development of non-destructive testing technology for thermal barrier coatings is of paramount importance for the quality assessment of coating preparation and service process. As a novel form of non-destructive testing technology, terahertz time-domain spectroscopy has been employed in a range of fields, including agriculture, the food industry, and biomedicine. It has also demonstrated considerable potential for use in the non-destructive testing of thermal barrier coatings. This paper presents a review of the detection of ceramic layer thickness, pores, stress, and failure using terahertz time-domain spectroscopy technology, with a particular focus on the latest advances in the detection of coating thickness and pore characterization. In conclusion, the current applications and future developments of terahertz time-domain spectroscopy for non-destructive testing of thermal barrier coatings are discussed.