A new dualdirectional extrusion (DDE) technique is applied on AZ31 Mg alloy at different extrusion ratios and temperatures by an extruder whose maximum load is 100t. In this experiment, the grain size is significantly reduced from 400 μm ascast to 6 μm asextruded when the extrusion ratio is 4.5; while at elevated extrusion ratio of 10.125, the grain size is reduced to 3 μm. The microhardness, compressive ratio, elongation and yield strength are all improved a lot and decreased with the increase of extrusion temperatures (except 250 ℃).