Abstract: Results of the experiments are given as follows:1. Variation of the fluid permeability in wood is extremly large. Even within the same tree species the fluid permeabilities in some wood samples may be 1—1000 times higher than those of the others. 2. The permeabilities in both coniferous and broadleaved species heartwoods are much lower than those in sapwoods. The fluid permeabilities in early and late wood of an annual ring vary with tree species. Such as Pinus yunnanensis, the fluid permeability in early wood is higher than that in late wood, but on the contrary in Pinus sylvestris var. monglica. As for Pinus massoniana it has the same permeability both in early and late wood. 3. The fluid permeabilities in wood of both coniferous and broadleaved tree species are much higher in longtudinal direction than those in cross direction. The latter varies in tangential and radial direction depending on coniferous or broadleaved tree species. The fluid permeability of coniferous wood in radial direction is a little bit higher than that in tangential direction, while in broadleaved wood it is a little bit lower in radial direction than in tangential one. 4. The fluid permeability in wood has no relation with its density. 5. The gas permeability in wood does not relate to the kind of gases. For example, the permeability of air, oxygen or nitrogen in wood is almost same, but it will be decreased as the wood moisture content increases, and will be become greater as the gas pressure increases and the pressure time puts off.