Al-Mg alloy (5xxx aluminum alloy) has good processability, corrosion resistance and weldability, but their medium-hardness limits their wear resistance. Based on the main alloy elements of 5xxx aluminum alloys, 0.14wt.% Zr and 0.35wt.% Er were added into Al-xMg-0.5Mn; the effects of different contents of Mg (Mg content up to 9.28wt.%) on the microstructure and friction and wear properties of high Mg aluminum alloy were studied. With the increase of Mg content from 2.96wt.% to 9.28wt.%, the (Al, Mg, Mn, Er, Zr) composite phases formed in Al-xMg-0.5Mn-0.14Zr-0.35Er alloy increased gradually; the size also increased gradually; their morphology changed from rod shape to fine fishbone shape, and finally forms uniformly coarse fishbone shape. When Mg content increases from 2.96wt.% to 9.28wt.% Mg, Er and Mg are often "concomitant segregation", mainly in the form of Al (ErxMg1-x) and Al (Erx(Mg, Mn)1-x). These composite phases change from massive to uniformly distributed (Al, Mg, Mn, Er) phases, which have a certain strengthening effect and can significantly improve the friction and wear performance of the alloy. After compound addition of 0.14wt.%Zr and 0.35wt.%Er, the wear mode of the alloy changes from the mixed wear (adhesive wear and abrasive wear: Mg content is 2.96wt.% - 5.15wt.%) to abrasive wear (Mg content is 5.7wt.% - 9.28wt.%). With the increase of Mg content from 2.96wt.% to 6.8wt.%, the wear resistance of the alloy increases gradually; when the Mg content increases to 8.0wt.% - 9.28wt.%, the wear resistance of the alloy tends to be stable, and the instantaneous friction and wear coefficient μ reaches the stable value of 1.11-1.15.