Abstract: An experimental investigation was carried out to deal with the unmatched problem between the gel-time and full-time in vacuum infusion process (VIP). By studying the thickness change of process part s prepared by VIP in different layers, an empirical formula related with resin flow distance, fiber layersp numbers and thickness was obtained and the feasibility of this formula was validated. Problems and defects existing in the practical process were analyzed and the improved experimental methods were also discussed to improve the process efficiency and products' quality in engineering.