In order to investigate the macroscopical mechanical performance of magnesium alloy material containing pore and the mechanism during distorting destructing, an accurate finite element model of magnesium alloy using the multiscales method was developed, and the macroscopic properties of material under the macroscopic tensile load using the developed constitutive model of multi-scales and finite element method was obtained. By analyzing the distortion results of meso-model through the multi-scales method, with macroscopical load increasing, the difference demonstrated on the macroscopic is very small, however, with the increase of the load step, the phenomenon that the ability of plasticity deformation of the meso-models which includes the cuboid pore decreased gradually remarkable and the phenomenon of stress centralized is more severity than the meso-models including cylindrical pore could be obviously observed during the process of deformation on the meso-models.