The Mg-11Gd-4.5Y-1Nd-1.5Zn-0.5Zr (wt%) alloy was pre-aged prior to hot extrusion. Pre-ageing treatment introduced uniform distribution of plate-like Mg₅RE precipitates, which transformed into nano-scale globular Mg₅RE particles by split and spheroidization during hot extrusion. These globular Mg₅RE particles contributed to continuous dynamic recrystallization by promoting the evolution of low misorientation sub-grain boundaries to high misorientation grain boundaries and caused grain refinement through grain boundary pinning. The improved mechanical properties were ascribed to the grain refinement, globular Mg₅RE and LPSO precipitates. The ratio of compressive to tensile yield strength is 1.2. The yield strength asymmetry was attributed to the deformation asymmetry of LPSO phase and non-isotropic deformation behaviors of Mg matrix in tension and compression.