The　microstructure　and　grain　refinement　of　Al-4.5Er-1Zr-1.5Ti　master　alloy　were　analyzed　by　the　refinement　experiment,　OM,　SEM　and　XRD.　The　results　show　that　the　grain　size　of　pure　aluminum　is　reduced　from　14,000μm　to　202μm　by　Al-4.5Er-1Zr-1.5Ti　master　alloy,　which　is　mainly　due　to　the　nucleation　promoted　by　Ti2Al20Er,　Al3Er　and　Al3Ti.　Plastic　deformation　further　improves　the　refining　effect　of　the　material　by　improving　the　primary　phase　size,　and　the　Al-4.5Er-1Zr-1.5Ti　−2ARB　can　refine　the　pure　aluminum　from　202　mμm　to　150μm,　and　the　refinement　was　increased　by　25.7　%.　The　master　alloy　showed　a　better　refinement　effect　in　Al-5Cu　alloy　than　pure　aluminum,　with　a　grain　size　of　92μm　and　a　refinement　improvement　of　97.8　%.　©　2024　The　Authors