AZ31 Mg alloy was prepared through equal channel angular pressing (ECAP) by Bc route in two different dies, in which the intersecting angles between channels are 90° and 120° respectively. Microstructures and tensile behaviors of the processed material at room temperature were investigated. The 90° die could provide more effective grain refinement in one pass of ECAP. But after multiple passes of deformation and when the total strain reached about 8, the alloy processed by the two dies acquired tiny homogeneous equiaxed grains with a mean size of 1 - 5μm and possessed similar mechanical properties with a large ductility of above 45% and a yield strength of 100 MPa,which are much different from the ductility of 18% and the yield strength of 200 MPa for the conventionally extruded material. The X-ray diffraction results show a great difference on peak of the basal plane (0001) between sections perpendicular and parallel to the extrusion direction for the conventionally extruded alloy but the difference lowers much for the ECAP processed alloy. The ultra-fine-grain microstructure and the texture or scattered orientation of the basal plane (0001) has the great effect on the alloys mechanical behavior.