Abstract: In RTM, it needs pre-placing fibrous preform into the mold. It is most probable to create an edge effect, which offers injected resin paths of least resistance due to the variation of fibrous preform structure and the shape and dimension of the mold. The edge effect may drastically affect resin flow front advancement and the distribution of pressure fields. In this paper, simulations are carried out with the approach of equivalent permeability, and the resin flow front curve and pressure fields with flow channels are obtained. The studies demonstrate that on the one hand the edge effect may lead to the unwanted effect on resin flow fields to form defects——dry spot, on the other hand it may be used to enhance the mold filling process: reduction of mold and injection pressures at constant flow rate injection; shorter fill time at constant pressure injection.