The　properties　of　aluminum　alloys　are　developing　towards　high　specific　strength,　high　specific　modulus,　high　damage　tolerance,　heat　resistance　and　corrosion　resistance.　Microalloying　is　an　important　means　to　improve　the　properties　of　aluminum　alloys.　A　large　number　of　studies　have　shown　that　adding　cheap　element　Er　to　aluminum　alloys　can　play　an　effective　role　in　microalloying.　In　this　paper,　the　structure　and　precipitation　of　Al-Er　phase　are　summarized,　and　the　role　of　Er　in　several　types　of　industrial　aluminum　alloys,　cast　aluminum　alloys　and　3D　printed　aluminum　alloys　is　reviewed.　Microalloying　element　Er　can　form　nano　sized　Al3Er　strengthening　phase　in　aluminum　alloys,　under　the　same　atomic　content,　the　dispersion　precipitation　strengthening　effect　of　Al3Er　is　more　significant　than　that　of　Al3Sc.　The　addition　of　Er　element　and　the　precipitation　of　Al3Er　phase　can　obviously　refine　the　aluminum　alloys　structure,　increase　the　recrystallization　temperature,　promote　the　precipitation　of　main　strengthening　phases,　and　greatly　improve　the　strength　or　plasticity　of　aluminum　alloys.　Er　can　also　form　high　stability　Al3(ErZr)　and　other　composite　strengthening　phases　with　Zr　and　other　elements,　through　its　multi-level　action　mechanism　on　dislocation　substructure　and　grain　morphology　regulation,　Er　can　effectively　improve　the　comprehensive　properties　of　aluminum　alloys,　such　as　heat　resistance,　corrosion　resistance　and　3D　printing　crack　suppression.　At　present,　the　microalloying　element　Er　and　its　composite　microalloying　have　been　successfully　applied　in　Al-Cu　system,　Al-Mg　system,　Al-Zn-Mg　system,　some　cast　aluminum　alloys　and　3D　printed　aluminum　alloys,　and　become　an　important　method　to　improve　the　comprehensive　properties　of　aluminum　alloys.　©　2022　Materials　China.　All　rights　reserved.