Terahertz (THz) technology is undergoing a rapid development in biomedical applications. Researchers have made a series of important achievements in the study of biological samples on various levels such as biomolecules, cells, tissues, and individual organisms, which provide new insights and innovative approaches for biological research and biomedical diagnosis. In this review, the progress of applying THz technology in biomedical studies has been summarized, including three key aspects, namely, spectroscopic detection, imaging, and biological effects. The challenges encountered in THz biomedical applications have been discussed, and the future development directions have also been envisioned.