The development history of quantum cascade lasers (QCL) is reviewed. The research progress of ma. terials and devices in quantum cascade lasers with typical wavebands such as mid-infrared, long-wave infrared, and terahertz is summarized. Meanwhile, the applications of QCL in the fields of composition detection, free-space opti. cal communication and directional infrared countermeasure are introduced. Finally, the development trend of QCL technology is summarized.