For single photon counting imaging technology to detect weak target signal, low signal-to-noise ratio, and unclear target area of the obtained image, serious background noise and other problems, a single-photon detection system based on solar-blind ultraviolet is designed by using 270±5 nm solar-bind UV filter, microchannel plate image intensifiers (MCP) with irnage gain >10 5 and scientificgrade complementary metal oxide semiconductors (sCMOS) with a mazimum resolution of 1 504×1 504. The system uses time sequence control to obtain single-photon spot images. To highlight the target area in the image, the improved morphological top-hat transformation algorithm is used to enhance the spot target area. Then, the image is binarized by the triangular threshold method, and the coordinates of the target area are extracted by using the connected domain. Finally, the area extremum algorithm is used to count single photons in the target area of the original image. The article conducts a series of imaging with a single exposure time of 80~ 100 ns and data processing experiments on ultraviolet light sources. The results show the feasibility of the designed single-photon imaging detection system and photon counting algorithm.