To prepare novel polyimides with enhanced thermal stability and low melt viscosity, a novel three-branched phenylethynyl-terminated imide oligomer was introduced. The oligomer can be used to prepare high performance resin-based composite material via resin transfer molding (RTM) due to its low melt viscosity (<2Pa.s) between 250°C and 320°C. The cured resin exhibits excellent thermal stability and higher glass transition temperature than PETI series as a result of the introduction of star-branched units. In this research, the rheological properties of the oligomer were measured and numerically fit with the dual Arrhenius model to predict the progression of the viscosity during cure. The calculated kinetic activation energies for gelation with two different Arrhenius equations, 120.8kJ/mol and 164kJ/mol, respectively,had some differences. The numerical results were compared with the experimental measurements, and it was found that the model predicts the experimental observations quite well.