Directional solidification of metal/gas eutectic (Gasar) is a novel process for fabricating porous metals with oriented pores parallel to the solidification direction. By use of the developed Gasar apparatus, lotus-type porous silver samples with different porosities have been fabricated in oxygen atmosphere. In this paper, we studied the effects of gas pressure on porosity, pore nucleation, pore size and distribution. It is concluded that the porosity and the pore size in the lotus-type porous silver were significantly affected by pressures of oxygen. The porosity increases with increasing pressure of oxygen. The average pore diameter decreases with increasing of oxygen pressure.