Air permeabilities of four kinds of wood chip aggregates of different species such as poplar, birch, basswood and elm were experimentally studied. The results showed that when dry density of chip bed maintained as constant, air permeabilities of the materials decreased with the increasing of moisture content(MC). When MC was around 30%～80%, the variation of air permeabilities with respect to MC was not as much as that when wood chip was changing from oven dry to about 10% MC. This visualizes that from oven dry upto 10% MC, the influence of MC on air permeabilities of wood chip bed is very significant. When MC maintained as constant, air permeabilities decreased with the increasing of chip bed density.