Al-30Zn-3Cu-2.5Si　high　Zn　Al-based　alloy　was　taken　as　the　research　object,　the　effects　of　Er　and　Zr　on　the　microstructure　and　mechanical　properties　of　as-cast　and　heat-treated　alloys　were　investigated,　and　the　action　mechanism　was　analyzed　and　discussed.　The　results　show　that　the　grain　size　of　the　alloy　can　be　obviously　refined　by　adding　0.10wt%　Er　and　0.10wt%　Zr,　the　average　grain　size　is　reduced　from　74.28　mu　m　to　60.01　mu　m,　and　the　grains　of　alpha-Al　are　changed　into　fine　equiaxed　grains.　The　addition　of　rare　earth　elements　Er　and　Zr　can　form　fine　particles　of　Al-3(Er,　Zr)　in　the　alloy　and　pin　dislocations　to　improve　the　mechanical　properties　of　the　alloy.　After　adding　Er　and　Zr,　the　tensile　strength　of　as-cast　alloy　increases　from　323.01　MPa　to　358.29　MPa,　which　increases　by　10.93%;　the　yield　strength　increases　from　309.33　MPa　to　315.00　MPa,　which　increases　by　1.83%;　the　elongation　barely　changes.　The　tensile　strength　and　yield　strength　of　the　alloy　strengthened　by　solution-aging　heat　treatment　are　449.48　and　408.51　MPa,　which　are　25.45%　and　29.68%　higher　than　those　of　the　as-cast　alloy,　respectively.　The　coarse　second　phase　exists　at　the　grain　boundary,　which　results　in　the　poor　elongation　of　the　alloy.