Abstract: Terahertz （THz） technology deals with a wide range of disciplines,such as electromagnetics, optoelectronics, semiconductor physics, material science, and micro-technology. Its applications in information science, biology, medical, astronomy, and environment science are introduced. THz sources and detectors, as the research frontiers, are the key devices in the THz applications. The research progress of THz terahertz oscillators and detectors is reviewed.