Abstract: A statistical model is developed to study the flowing performance of resin fluid inside fibrous assemblies during the impregnation process. The probability of a fluid move is the function of the variation of a fiber/resin system's energy before and after moving. The energy of the fiber/resin system includes its internal energy, which is the Hamiltonian, and the work done by the interfacial tension between the fiber and resin, by the pressure driving the resin, and by the friction loss when the resin flows through fibrous assemblies, which is expressed in thermodynamic terms as pressure. Simulation is performed to study the performances of a selected fluid flows through fibrous assemblies, i.e. water through nonwoven PET fiber mats and unsaturated polyester resin through glass woven fabrics. To verify the model, a set of experiments illustrates the water through the fiber mats with different fiber volume fractions and the resin through the woven fabric with different influxes. Simulation results are in good agreement with experiments, indicating good prospect of the model used in this area.