Abstract: In this paper, the rheological behavior of epoxy resin (EPON862) for resin transfer molding (RTM) was studied with DSC analysis and viscosity experiments. A rheological model based on dual-Arrhenius equation was established and used to simulate rheological behavior of the resin. The estimated viscosity of the model was in good agreement with that of the experiments. The processing window of the resin system can be well determined for the process based on the developed model. It is shown that the optimum processing temperature of the EPON862 resin for RTM process is 50℃, at which the resin can keep the viscosity less than 300 cP for 50 min. The rheological model is important for processing simulation and quality control of RTM processing for high performance composites.