The fundamental principles of single?photon imaging technology are introduced, along with an analysis of its advantages of high sensitivity, high temporal resolution and high photon utilization efficiency. The technical characteri?stics of single?point scanning and multi?pixel single?photon imaging are elaborated, with discussions on their applications in scenarios such as long?range imaging, underwater imaging, and imaging in complex environments. Principles of traditional single?photon imaging algorithms and deep learning?based algorithms are presented, followed by a comparative analysis of their application effects under conditions of sparse echoes, strong noise and multi?peak signals. The outlook for the future development of single?photon imaging technology is proposed, highlighting that innovative hardware systems, optimized imaging algorithms and interdisciplinary technology integration will further advance the field toward higher accuracy, efficiency and intelligence.