Abstract: Phosphorescent carbon dots (CDs) have great potential in energy, information, biomedicine, and other fields because of their long lifetime, long wavelength emission, and low background interference. However, there are still some challenges in their preparation and understanding their luminescence mechanism. For example, their triplet states are easily affected by the external environment, which leads to phosphorescence quenching. The phosphorescence mechanism and the effects of element doping, rigidity of structure, and conjugated structure on their properties are reviewed to address these issues. The synthesis methods include one step and two step methods. The uses of phosphorescent CDs are summarized and include information security, light emitting diodes, ion detection, and biological imaging. The existing problems are discussed and development directions are proposed.