Abstract: With the increasing global energy shortage and environmental pollution problems, hydrogen energy, with the advantages of high calorific value and environmental friendliness, has become one of the most promising energy sources. As a green and sustainable hydrogen production method, the electrocatalytic hydrogen evolution reaction (HER) has attracted wide attention. At present, catalysts are always the core issue in both the basic research and applied research of HER. Single atom catalysts (SACs) show excellent catalytic activity and stability in the HER process due to their maximum atomic utilization efficiency and unique structure and performance. In this paper, the synthesis methods of SACs used in HER in recent years, including preparation methods such as pyrolysis, deposition, liquid phase synthesis and etching were reviewed. In addition, various physical chemical performance characterization and density functional calculation methods used to explore the structure-catalytic relationship between SACs and HER were summarized. Finally, the deficiencies of SACs for HER were analyzed and summarized to provide a valuable theoretical reference for the design and preparation of cheap and effective SACs for HER and improve their practical application value.