Thermal radiation is a fundamental physical process that refers to the spontaneous emission of electromagnetic energy from objects with temperatures above absolute zero due to the thermal motion of particles. Most thermal radiators lack directionality, resulting in energy loss in unnecessary directions, which reduces the efficiency of many thermal devices and applications. In practical applications, thermal radiators are usually required to exhibit different thermal radiation capabilities in different directions, therefore, controlling the directionality of the thermal emission is crucial in efficient heat transfer. The study of directional thermal radiation is of great significance in thermal imaging and sensing, radiative cooling, infrared encryption, and energy utilization. The review first describes the difference between traditional and directional thermal radiation, as well as the potential value of the latter at the frontiers of science. Subsequently, based on the characteristics of thermal radiation, it systematically organizes the research progress of domestic and foreign scholars in directional thermal radiation in terms of both narrowband directional thermal radiation and broadband directional thermal radiation. Finally, future research trends in this field are envisioned, and major challenges are analyzed, aiming to provide theoretical guidance and practical insights for the further development of directional thermal radiation technology.