Electromagnetic metamaterial is a kind of artificial structural material whose basic unit is subwavelength metal structures. It is an important foundation for the development of THz devices. Based on the introduction of electromagnetic metamaterial structure principle, this paper describes the application of electromagnetic metamaterial absorber, polarization devices, broadband devices, modulators, near-field terahertz sensors and other devices. As one of the most important subfields in terahertz modulation technology, the research of terahertz metamaterial has profound influence on the future development and commercialization of terahertz technology.