The　microstructure　and　segregation　of　7N01　aluminum　alloy　microalloyed　with　Er　and　Zr　before　and　after　homogenization　process　at　470　°C　for　24　h　have　been　investigated　using　transmission　electron　microscope　(TEM),　and　scanning　electron　microscope　(SEM)　equipped　with　energy　dispersive　X-ray　spectroscope　(EDS)　and　transmission　electron　detecter　(STEM).　SEM　images　and　EDS　line　scan　results　showed　that　there　were　dendritic　segregation　of　Mg　and　Zn　and　micron-sized　primary　phases　along　dendrites　in　the　as-cast　alloy.　The　primary　phases　were　mainly　Al2Mg3Zn3　containing　Al,　Zn,　Mg　and　Mn.　And　a　small　amount　of　primary　phases　were　the　particles　containing　Al,　Zn,　Mg,　Mn,　Cr　and　Er　and　the　particles　containing　Al,　Zn,　Mg,　Er,　Mn,　Fe　and　Cr.　After　homogenization　at　470　for　24　h,　dendritic　segregation　of　Mg　and　Zn　was　eliminated,　Al2Mg3Zn3　and　the　particles　containing　Al,　Zn,　Mg　and　Mn　were　basically　dissolved.　The　particles　containing　Al,　Zn,　Mg,　Mn,　Cr　and　Er　and　the　particles　containing　Al,　Zn,　Mg,　Er,　Mn,　Fe　and　Cr　remained.　Meanwhile,　TEM　and　STEM　images　showed　that　a　large　number　of　secondary　phases　appeared　after　the　homogenization,　which　were　mainly　distributed　in　the　inter-dendrite　area.　EDS　results　showed　that　the　block-shaped　and　rod-shaped　phases　with　the　width　of　10-70　nm　and　length　of　100-500　nm　were　the　particles　containing　Al,　Cr　and　Mn　or　Al,　Mg,　Cr　and　Mn,　and　the　ellipsoid　secondary　phase　with　the　size　of　50-100　nm　was　MgZn2.　©　2020　Trans　Tech　Publications　Ltd,　Switzerland.