This experiment determined the permeability of the woven fabric preforms impregated by resin during Resin Transfer Molding (RTM) process and capillary pressure generated at the advancing flow front due to the resin surface tension. The unsteady state isotropic/anisotropic permeabilities were measured as a function of porosity. It was found that the permeability of unsteady state was larger than that of the steady state, which depended highly on porosity and structural characteristics of fibrous preforms. The capillary proessure corresponding 25% of the resin injection pressure at the gate was induced when the porosity was 0.469. Accordingly, capillary pressure should be considered as a process condition in order to analyze the resin flow phenomena during the RTM process. In addition, the form factor describing fiber orientation and pore distribution for the random glass fiber mat was obtained by measuring the dynamic contact angle between glass fiber and silicon oil. Consequently, the form factor determined in this study will serve data to predict capillary pressure induced during the RTM process.