Photodetectors have important value in applications such as detection, communication, imaging, and guidance. In the infrared band, commonly used detectors include mercury-cadmium-telluride detectors, quantum-well detectors, and type-II superlattice detectors. However, owing to differences in the operation temperature, noise, and dark current, the development and application of various detectors are limited. Meanwhile, quantum cascade detector (QCD) can achieve the directional transport of photogenerated carriers without the need for bias voltage utilizing the principles of intersubband transition and resonant tunneling as well as the phonon ladder design concept. QCD is characterized by low dark current, excellent noise performance, outstanding high-frequency performance, and a detection wavelength range spanning from infrared to terahertz bands, offering innovative pathways for the future development of infrared and terahertz photodetectors. This article initially examines the working principles, models, and device physics of QCD. It then emphasizes on recent research developments domestically and internationally, including advancements in material systems, optical coupling optimization, active region design and optimization, and the synergistic integration of QCD with quantum cascade lasers. Furthermore, a comparative analysis of QCDs and other mainstream infrared detectors is presented. Finally, the future opportunities and challenges of QCD are summarized and discussed.