Abstract: Mid-infrared (mid-IR) photodetectors are a crucial component of modern optoelectronic technology, and play a vital role in industrial inspection, aerospace remote sensing, and national defense. The application of infrared detection began during World War II and has undergone four generations of development. This paper discusses the historical development and main types of mid-IR detectors currently in use, as well as future growth directions. This technology is in a stage of rapid development; new materials such as topological materials, two-dimensional materials and heterojunctions are being explored, while metasurfaces and other structures have enhanced detector performance and are being exploited to develop new optical parametric detectors. Furthermore, the integration of artificial intelligence into this field has opened up new opportunities for its development, and will bring new changes that can meet the needs of various sectors for high-performance, low-power, and miniaturized infrared detectors.