This paper gives a brief review on the terahertz technology,with the emphasis on the development of shaped reflector antenna techniques. The applications of shaped reflector antenna techniques to terahertz quasi-optical system,terahertz communication system,and terahertz imaging system are discussed. Shaping technique can transform the output beam to desired field distribution according to the law of energy conservation and equal-optical path principle. Shaped reflectors can therefore extend the functionality of conic reflectors. Shaping technique will extend the applications of reflector antenna in terahertz range,and enhance the amplitude and phase performance of a terahertz system.