The terahertz (THz) band offers potential advantages, such as large bandwidth, high resolution, and strong penetration capability. It fills the gap between microwave and infrared technologies, and exhibits tremendous application potential in fields such as next-generation sensing, imaging, communications, biomedical engineering, and security inspection. As an important technology capable of effectively regulating key parameters of terahertz waves, including propagation direction, phase, and amplitude, metasurfaces overcome the inherent weak interactions of materials in the terahertz band, thus becoming a focus of research in recent years. With the continuous development of information technology, traditional static metasurfaces struggle to adapt to dynamic environments, making it necessary to enhance their dynamic regulation performance. By incorporating tunable materials or applying additional stimuli, terahertz-tunable metasurfaces achieve dynamic, real-time regulation of terahertz waves, attracting attention across a wider range of applications. This review focuses on the latest advancements in tunable metasurface technologies. It systematically reviews the regulation methods and response mechanisms of terahertz tunable metasurfaces, introduces tunable materials or structures, such as liquid crystals, semiconductors, phase-change materials, and mechanical structures, and summarizes research work on various types of terahertz-tunable metasurfaces. Secondly, it focuses on the application progress of terahertz tunable metasurfaces in major fields including optical imaging, wireless communication, and biosensing, and demonstrates the tremendous development potential of terahertz tunable metasurfaces in these applications by highlighting outstanding research. Finally, it summarizes the challenges faced by terahertz tunable metasurfaces in developing efficient regulation mechanisms, achieving high integration and multifunctionality, reducing costs, and improving manufacturing stability, and presents an outlook on future research and development.