In accordance with preparation process of open-cell aluminum foam, a novel simplified model of pore s structure was proposed to exploit the performance of the through-holes, which connect neighboring cells, on the elastic module and compressive collapse stress of porous aluminum alloy. It is shown that the results coincide with experiments in terms of elastic module and plastic collapse stress. Stress concentration neighboring the through-hole between neighboring cells was manifested by unit cell model. On account of significant effect of through-hole’s variation on porosity, the sensitivity of mechanical properties of open-cell aluminum alloy on porosity could be explained by stress concentration on the through-hole between neighboring cells.