The　6061　aluminum　alloys　with　different　content　of　erbium　were　prepared.　The　erbium　content　was　optimized　by　measurement　of　grain　refining　effects　and　tensile　strength.　After　solid　solution　treatment　of　the　alloy　with　optimized　erbium　content　at　505　°C　~　595　°C　for　4　h.　and　then　ageing　at-160　°C　~　200　°C　for　3　h.,　the　grain　size　decreased　with　the　content　of　erbium,　achieving　the　most　effective　grain　size　refinement　at　the　erbium　content　of　0.15wt.%.　The　tensile　strength　of　as-cast　alloy　could　reach　up　to　243　MPa　at　the　erbium　content　of　0.15%.-Combined　with　the　microstructures　and　mechanical　properties,　the　erbium　content　of　0.15%　was　the　optimized　content,　and　heat　treatments　of　ageing　at　180　°C　for　3　h.　followed　by　solid　solution　at　565　°C　for　4　h　were　suggested.　©　2017　Trans　Tech　Publications,　Switzerland.