Abstract: The hot plastic deformation can effectively improve the mechanical properties of Mg-Ni-Y alloys containing the long-period stacking-order (LPSO) phase.The effects of hot-rolling deformation on the microstructure and mechanical properties of Mg₉₇Ni₁Y₂ alloy were studied by scanning electron microscopy, electron backscattering diffraction and tensile testing.The results show that the LPSO phase is distorted during the hot-rolling.As the hot rolling deformation amount increases from 40% to 70%, the angle of the LPSO distortion increases from 11° to 39°, and some of the LPSO fracture.In addition, dynamic recrystallization occurs at the deformation of 70%, thereby leading to more refined grains.Under the joint action of LPSO phase twist strengthening, fine grain strengthening and dispersion strengthening, the strength of the alloy increases with the increase of hot-rolling deformation.The alloy with the largest deformation (70%) reaches the highest strength:yield strength and tensile strength up to 276 MPa and 358 MPa, respectively.