As a potential low-cost and high energy density energy storage technology, rechargeable Mg batteries (RMBs) have shown renaissance in the last decade, since the first realization of Mg electrochemical deposition nearly a century ago. Based on the Chervel phase Mo6S8 cathode, metal Mg anode, and organohaloaluminate electrolyte, the first RMB prototype was constructed, and more and more investigations are being committed to advance RMB system after that. In this review, we first overview the current status and challenges of Mg-ion techniques. Recent developments on critical components of RMBs, i.e., cathode and anode materials, are then analyzed systematically. Based on these understandings on the state-of-the-art RMBs, potential improving strategies are proposed to provide insights on future development of RMBs.