A kind of Al-Mg-Si alloy contained Zr and Er element for sheet was prepared.The alloy composition is Al-0.8Mg-1.0Si-0.8Cu-0.2Mn-0.15Zr-0.3Er.As-cast and homogenized microstructure of the alloy prepared was observed by transmission electron microscope（TEM）

X-ray diffraction（XRD）

scanning electron microscope（SEM）

energy dispersive spectrum（EDS）and optical microscope（OM）.Meanwhile

the types and changes of precipitation phase in as-cast and homogenization state were analyzed.The results indicate that with Er and Zr addition in casting ingot

the equiaxed grain in the alloy prepared can be observed

and the second phases mainly existing in casting alloy include Mg2Si、Al1.9CuMg4.1Si3.3、CuAl2、Al4Mn3Si2、primary Al3Er、Al3Zr andβ-Si.After homogenization treatment

the second phase particles are distributed more uniformly

improving microstructure of the alloy

and Mg2Si、Al1.9CuMg4.1Si3.3and CuAl2 phases are fully dissolved into the alloy during homogenizing treatment.There are coherent Al3 Er particles precipitate from supersaturated Er solution

and the Al3（Er

Zr）composite phase with a core-shell structure is formed.