Abstract: Mathematical models that objectify both resin meso flow between adjacent yarns themselves and micro flow in yarns were established for textile preform unit cell. Based on the principle of minimum potential energy, geometric model of unit cell in slack state was built. Meanwhile, the deformation of unit cells influenced by mold compression was analyzed, and the geometric models of different compressed states were established. According to the mathematical model solution of resin flowing in unit cell, fields of flow velocity and pressure were obtained. Forecasts of the preform permeability were then conducted. Permeability of a group of unit cell was predicted.The effects of compression deformation of preform on permeability were studied. Results show that with the increase of deformation amount, the permeability gradually decreases. Through the experimental results and data analysis, the correctness of models and the forecast method were verified.