The　effect　of　Er　and　Si　on　the　evolution　of　precipitates　in　Al-Cu-Mg　alloys　during　elevated　temperature　exposure　was　investigated.　The　Er　segregation　in　0＇-Al2Cu　precipitates　and　Si/　Mg　co-segregation　at　the　interfaces　of　0r/Al　matrix　are　experimentally　observed　in　Al-Cu　-Mg-Si-Er　alloy,　which　finally　contributes　to　the　heat　resistance　of　the　Al-Cu-Mg-Si-Er　alloy.　Si　enhances　formation　of　the　Q＇＇　phases　as　nucleation　sites　for　the　0＇　phases,　resulting　in　a　refined　distribution　of　0＇　phases.　Al-Cu-Mg　alloy　with　high　strength　as　well　as　high　thermal　stability　is　obtained　by　co-adding　Er　and　Si.　The　high-temperature　yield　strength　(YS)　of　Al-Cu-Mg-Si-Er　alloy　at　225　degrees　C　are　increased　by　37　MPa　compared　with　that　of　Al　-Cu-Mg　alloy.　Simultaneously,　the　addition　of　Er　significantly　increases　the　elongation　of　Al-Cu-Mg-Si-Er　alloy.(c)　2023　The　Author(s).　Published　by　Elsevier　B.V.　This　is　an　open　access　article　under　the　CC　BY-NC-ND　license　(http://creativecommons.org/licenses/by-nc-nd/4.0/).