Abstract: The stiffened panel of the typical aerospace carbon fiber reinforced polymer composite structure was studied by analyzing the characteristics of the U3160 unidirectional fabric organization structure. The compression response of the fiber bundle was theoretically modeled according to the compression deformation state of the fiber bundle. Based on the fiber bundle compression model, the thickness change responses of the U3160 unidirectional fabric preform with the 0°/45°/90°/-45°stacking sequence under the influence of compressive stress were forecasted. The permeability model of the fabric preform under the effect of compression stress was formed. Based on the fabric compression model, the equivalent permeability model of fiber bundle was established. According to the tensor theory, the equivalent permeability model of the 0°, ±45° and 90° ply fabric was established respectively. By using the series-parallel relationship of permeable media, the comprehensive characterization model of permeability in each characteristic zone of stiffened panel was established. Based on the PAM-RTM flow simulation software, the permeability of the partition zone was defined, the flowing behavior of resin in the stiffened-panel fabric preforms was simulated during the filling process, the technological parameters was optimized to determine the final filling program, and the models of stiffened panel were made to carry out the molding experiment to verify the rationality of filling program. The work provides the theoretical basis for the successful production, which can be used to finally guide the practice.