In the present study, an attempt is made for the first time to reinforce long-period stacking ordered (LPSO) MgY1.06Zn0.76Al0.42 (at.%) alloy with 0.5, 1.0, and 1.5 vol% of nano-Al2O3 particles to form nanocomposites. Microstructure characterization revealed the ability of nano-Al2O3 in inhibiting the formation of 14H LPSO phases in the nanocomposites during solidification. Homogenization at 723 K (450 A degrees C) for 2 h led to the subsequent precipitation of fine Mg-Y-Zn-Al precipitates (a parts per thousand currency sign1 A mu m) in the nanocomposites. The fine Mg-Y-Zn-Al precipitates and nano-Al2O3 particles were established to be active in promoting dynamic recrystallization (DRX) of alpha-Mg via particle-simulated nucleation during extrusion, which was responsible for weakening the basal texture in the nanocomposites and improving failure strain. As a result, failure strain was significantly increased from 10.8 % in the monolithic alloy to beyond 15 % in the nanocomposites with the highest strength among nanocomposites achieved in NC5 (nanocomposite reinforced with 0.5 vol% of nano-Al2O3 particles).