Abstract: The viscosity of epoxy resin was tested by viscometer, and an engineering viscosity model was constructed by the fitting method. In this simulation, the viscosity model was applied to predict the flow process of epoxy resin with different initial temperatures by using PAM-RTM. The influence of the viscosity change of epoxy resin on resin transfer molding (RTM) was discussed in detail. The results show that the filling time of RTM decreases first and then increases as the initial temperature increases, and the shortest filling time is acquired at 40℃. The viscosity change of epoxy resin has remarkable influence on the RTM of large scale structure.