Abstract: The chemorheological behaviors of bismaleimide resin (QY8911-4) for Resin Transfer Molding (RTM) were studied. A chemorheological model of the resin was developed based on dual-arrhenius equation. The estimated viscosity values of the established model are in good agreement with the experimental ones.The model was used to determine the critical low viscosity windows of the resin system for RTM processes. The optimum processing parameters of QY8911-4 resin for RTM are 100 ℃~110 ℃ at which the viscosity of the resin will be less than 200 cP within 55 minutes. These parameters are essential for the manufacture of structure composites with high fiber content. The longer pot life of the resin also can be obtained with low working temperature between 90 ℃ and 100 ℃, in which the viscosity of the resin can keep less than 800 cP. The developed model is important for processing simulation, parameter optimization and quality control for RTM processes.