Zn1 xMgxO alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Znl-xMgxO films with different magnesium contents on polar (0001) and nonpolar(10(1)0) ZnO substrates.The nanoscale structural features of the grown alloy films as well as the interfaces were investigated.It was observed that the cubic phases of the alloy films emerged when the Mg content reached 20％ and 37％ for the alloy films grown on the (0001) and (10(1)0) ZnO substrates,respectively.High-resolution transmission electron microscopy images revealed cubic phases without visible hexagonal phases for the alloy films with more than 70％ magnesium,and the cubic phases exhibited three-fold and two-fold rotations for the alloy films on the polar (0001) and nonpolar (1010) ZnO substrates,respectively.This work aims to provide references for monitoring the Zn1-xMgxO film structure with respect to different substrate orientations.