Abstract: The photon-counting detectors with great application potential, have brought technological innovation to radiation imaging fields. With energy resolving capability, photon-counting detectors will help to enhance radiation image quality, lower radiation dose and increase detection effectiveness. Nowadays, low-energy detection fields including medical diagnostics and luggage inspection have seen extensive and in-depth research on photon-counting imaging technologies. For instance, numerous advancements have appeared in energy spectrum CT, breast inspection, PET, etc. There are, however, not many investigations on photon-counting detectors for the detection of medium and high energy (MeV) rays. To meet the demands of detecting signals with medium to high energy and with high saturation count rate, further technical problem must be solved. This paper primarily introduces photon-counting imaging technology in terms of its features, advantages, latest research on X/γ ray imaging systems for medical and security use, and challenges it faced. In addition, its application status and technical difficulties that need to be broken through in large container inspection area are analyzed.