By regulating the pressure to cont rol the volume f raction of fibers V
f , the saturated permeability alongthe thickness of the fiber bed was measured by the unidirectional saturated flow method. The influence of pressureon V
f was investigated. Several factors which affect the permeability were studied , including V
f , the number of layers of the fiber bed , the ply stacking sequence and the kinds of fibers. The result s indicate that the degree of increaseof V
f with pressure decreases when V
f exceeds a critical value. The number of layers does not affect the permeabilityfor the unidirectional and bidirectional ply stacking while for the plain weave the permeability decreases with thenumber of layers. In addition , the kinds of fibers influence the permeability remarkably.