Single-photon detector can detect very weak light with high sensitivity, which has been widely used in the field of civil and national defense. With the development of technology, in addition to the optimization and improvement of traditional photodetectors, other new photodetectors have also been greatly developed and important technical achievements have been made. In order to deeply understand the development status and trend of single-photon detectors, the key information in research status, technical difficulties, and latest technological breakthroughs of representative single-photon detectors were summarized. The advantages and disadvantages of traditional single-photon detectors such as photomultiplier tube and avalanche photodiode were analyzed as well as the future technical development direction. At the same time, the superconducting nanowire single-photon detectors and avalanche photodiode based on new 2-D materials with good photoperformance and great development potential were introduced. And the future direction was prospected.