Abstract: The relation between the shear stress and shear rate in the Newtonian law was shown by the relation between the stirring torque and revolution through the theoretical analysis. By means of the relation between the stirring torque and the revoludon,not only the rheological characteristic of the molten A1 alloy can be identified, but also the effect of the increasing viscosity can be determined. The method for the producing porous A1 can be conveniently controlled.