Rechargeable Mg-air batteries are a promising alternative to Li-air cells owing to the safety, low price originating from the abundant resource on the earth, and high theoretical volumetric density (3832 A h L -1 for Mg anode vs 2062 A h L -1 for Li). Only a few works are related to the highly reversible Mg-air batteries. The fundamental scientific difficulties hindering the rapid development of secondary Mg-air cells are attributed to the poor thermodynamics and kinetics properties mainly owing to the MgO or MgO 2 insulating film as the initial discharge product on air-breathing cathode, contributing to the increase of a large overpotential and a high polarization. Very recently, remarkable progress on rechargeable Mg-air batteries is trying to overcome the major limitations in organic electrolytes via the combination of the first-principle calculation and experimental study. Therefore, this progress report highlights a comprehensive and concise survey of the major progress in the history of secondary Mg-air batteries, and the detailed illustrations of corresponding reaction mechanisms. The overview is devoted to open up a new area for manipulating the nanostructures to control the ideal reaction pathway in novel cell configuration and to fully understand the future Mg-air battery with improved energy density and cycling ability.