As an excellent optical device, photodetectors have many important applications, such as communication technology, display technology, scientific measurement, fire monitoring, aerospace and biomedical research, and it’s of great significance in the research of nanotechnology and optoelectronics. Graphene, as the first two-dimensional (2D) single-element nanomaterial, has the advantages of high carrier mobility, high strength, high light transmittance and excellent thermal conductivity, and it’s widely used in various nano-optical devices. The great success of graphene has led scientists to extensive research on other 2D single-element nanomaterials. Recently, a group of novel 2D single-element nanomaterials have attracted a lot of attention from scientists because of its excellent physical, chemical, electronic, mechanical and optical properties. Furthermore, it has opened a new door for the realization of new and efficient photodetectors. The group of 2D single-element nanomaterials are called 2D-Xenes and used to make high-performance photodetectors. Currently, there are few studies on photodetectors based on 2D-Xenes, but some 2D-Xenes have been applied to photodetectors and reported. Some of these have excellent photodetection performance, such as high photoresponsivity (R), broad spectral response range, fast photoresponse speed and high specific detectivity (D^*). Based on the novel 2D-Xenes, this review explores the types and preparation methods of 2D-Xenes, and the working mechanisms of 2D-Xenes photodetectors. Finally, the challenges and development trends of 2D-Xenes in the future are discussed. The research of 2D-Xenes is of great significance for the development of high-performance photodetectors in the future, and is expected to be widely used in other nanoelectronics and optical devices.