Abstract: The numerical simulation of the vacuum assisted resin infusion (VARI) process of perforated sandwich composite was verified experimentally, and process optimization was presented thereafter. Firstly, the permeabilities of the fabric and holes of perforated core were obtained experimentally and numerically, respectively. Then, 3D simulation was carried out for the infusion process of the perforated sandwich composite structure and verified by real-scale infusion experiments. Finally, based on the simulation, the process was optimized by investigating the effects of injection position and type on the filling time and product porosity, and later a methodology was proposed to predict the filling time needed. The results show that the numerical simulation is in good agreement with the experiment. The flow patterns during the filling and the porosities of the perforated sandwich structures are in good match with experimental results. The filling time prediction method can be used for practical production instruction. The selection of proper parameters, such as injection position and type, can minimize molding time and product porosity.