Abstract: Flow front in fiber fabrics was tracked by VOF (volume of fluid) method combined with a porous medium model,and the entrapped air bubbles were captured by simulation.The formation of bubbles is due to the heterogeneous structure which causes the velocity difference with several flow front.The bubbles will migrate under the dynamic pressure.Moreover,the effects of pressure,viscosity and dual-scale porosity on impregnation velocity were studied,and the impregnation time was in propotional to the reciprocal of pressure,viscosity,or transverse permeability divided by tow porosity.The impregnation velocity was determined by the impregnation of micro channels while had nothing to do with the distance between two fiber tows.