Single atom catalysts, as catalysts with atomic scale, have a wide range of applications in the fields of hydrogen production, CO oxidation, photocatalysts, etc. Extensive efforts of experimental/theoretical studies show that the strong metal support interactions and the changes in electronic structure are the main reasons for the high selectivity and catalytic activity of the single atom catalysts. This paper mainly summarizes the recent researches on the preparation methods including coprecipitation method, successive reduction method and wet-impregnation method, catalytic performance and high catalytic selectivity of single atom catalysts. And finally, the prospects for future investigations of single atom catalysts are proposed.