Sponge rubber atmospheric pressure molding, is to contain sufficient blowing agent into the mold cavity, and then vulcanization foam. Note that the compound does not fill the mold cavity, leaving part of the space for the plastic foam expansion. Above the cavity to open a vent, so that when the rubber expansion of the cavity above the air discharge. Before adding the compound, first in the cavity of a piece of cloth or coated with a layer of talcum powder, vulcanization can be the lower rubber material to escape the gas discharge. Atmospheric pressure molding foaming requires a lower viscosity of the compound, so that the fluid in the cavity of good mobility, easy to expand. The foam structure obtained by this method may be an open-cell structure or a closed-cell structure depending on the variety and amount of the blowing agent and the vulcanization rate of the compound.