Abstract: T-stiffened skins widely used in aircraft industry nowadays were fabricated by integral molding technology of co-bonding in autoclave. A method of self-designed solid pressure testing was introduced to measure the pressure distribution in the T-stiffeners during fabrication. The resin flow and fiber compaction of T-stiffened skins were investigated by analyzing the bleeding quantity and stiffener thickness. The results indicate that the presence of significant resin flow in plane is induced by pressure difference distributing in the various zones of the stiffeners，which results in some manufacturing defects of rich resin and non-uniform thickness in the corner section of stiffeners. Theratios of the thickness of the corner to the web and to the flange are almost in the range of 1.1~1.4. Moreover，the resin flow and fiber compaction are remarkably influenced by tool assembly schemes，curvature radii and fillers.