Abstract: The process of molten aluminium infiltration withdifferent viscosity in a porous medium under low-pressure is investigatedthrough organic transport material simulation based on the principle ofsimilarity. Experiments indicate that the plane surface of infiltratingliquid advances perpendicularly and conforms to the law of fourth root. At acertain time t, the Reynold's number Re(t), the resistance coefficient\lambda (t) and the pressure loss can be calculated by correspondingformulas. It is found that the viscosity changes of molten aluminum in acertain range (5\%) have little influence on the infiltration velocity.The filling time in the simulation is compared with that for prototype,and a good agreement is found.