The terahertz air coherent detection technology is a broadband terahertz detection technology. Since the detection bandwidth is only affected by the pulse width of the probe laser, the response range of this technology can reach tens of terahertz, so after successful experimental research, it has become an important detection technology in the field of terahertz technology. The experimental principle and experimental optical path of the terahertz air coherent detection technology are introduced in detail, the research progress and improvement measures of the technology in recent years are summarized, and its detection performance and use characteristics are analyzed and discussed. This research can provide a good reference for the preliminary use of terahertz air coherent detection technology.