Quantum cascade technology, based on resonant tunneling and intersubband transitions in a multiple-quantum well or superlattice structure can generate light source and detect optical signals, it is the theoretical cornerstone of quantum cascade laser (QCL) and quantum cascade detector (QCD), which has wide application prospect in detection, remote sensing, communication, radar, and other fields. After three decades of research, quantum cascade technology has made significant progress in basic research, product performance, application system research and scene testing. In this paper, the principle and development history of quantum cascade technology are briefly introduced first. Subsequently, the calculation approaches of intersubband energy level structure and electron transport dynamics in quantum cascade devices are elaborated. Next, the research progress of quantum cascade technology is mainly reviewed, including mid- and far-infrared high power QCL, mid-and far-infrared widely tunable QCL, terahertz QCL, high performance QCD, and single-chip photonic integration of QCL and QCD. Finally, the commercially available QCL and QCD products, as well as their application status, are introduced.