Micro　alloying　is　an　important　way　to　improve　the　properties　of　aluminum　alloy,　so　choosing　appropriate　elements　and　controlling　the　amount　of　addition　to　obtain　optimum　alloying　effect　were　investigated　intensively.　It　was　found　that　Er　was　a　cheap　and　effective　micro　alloying　element.　Nano-scale　Al3Er　particles　form　in　Er-containing　aluminum　alloys,　and　composite　phase　Al3(ZrxEr1-x)　can　form　due　to　the　interaction　of　Er　and　Zr.　These　kinds　of　particles　are　thermally　stable,　thus　the　addition　of　Er　can　optimize　the　microstructure,　improve　the　mechanical　properties　and　hinder　the　recrystallization　so　as　to　improve　its　thermal　stability.　The　research　progress　of　Er-containing　aluminum　alloy　is　presented.　The　emphasis　is　laid　on　the　precipitation　of　Al3Er　and　Al3(ZrxEr1-x)　and　its　effect　on　the　microstructure　and　properties.　The　effect　of　Er　in　some　typical　commercial　alloys　is　also　summarized.