Terahertz technology has important application prospects in the fields of physics, biology, medical diagnosis, non-destructive testing, and wireless communication. As an excellent candidate for both terahertz oscillator and detector, Resonant Tunneling Diode(RTD) has received increased attention in recent years. RTD is a semiconductor device based on the quantum tunneling effect, which simultaneously provides a negative differential resistance and nonlinear current-voltage characteristics. As for detector, it has distinct features of room-temperature operation, small size, easy integration, and high sensitivity, which makes it particularly suitable for applications scenarios such as short-range, ultra-high-speed terahertz wireless communication and the internet of things. This review focuses on recent progresses and applications of terahertz RTD detectors, and aims to provide further perspective on it.