The rapid advancement of modern technology has made the detection of"low-slow-small"targets crucial in both civilian and military applications. With ongoing industrial upgrades and transformations, the widespread use of low-altitude, slow-moving, and small targets presents new challenges, especially in long-range detection. Long-range detection of"low-slow-small"targets using traditional detection technologies such as sonar, radar, radio, visible light, infrared, and lidar still faces many limitations. Single-photon lidar technology, with its excellent temporal and spatial resolutions, high sensitivity, and long-range detection capability, offers promising solutions to these technical challenges. This paper provides an in-depth analysis of the difficulties associated with long-range detection of"low-slow-small" targets and systematically reviews and compares existing traditional detection technologies. Furthermore, this study explores the application prospects and technical challenges of single-photon lidar technology in the future detection field of"low-slow-small"targets, providing support and guidance for enhancing detection system performance and advancing related technologies.