In this study, heat transfer and melting process in a co-rotating twin screw extruder are studied based on two typical screw configurations, screw element and kneading blocks staggered 45°. In order to estimate the melting ability of two configurations quantitatively, FEM software, FLUENT is adopted to simulate the cases. It could be concluded that kneading blocks have higher temperature rise and more liquid fraction than screw element, and it takes less time and less distance for kneading blocks to finish melting. Simulation results also show that kneading blocks have more viscous dissipation than screw element. Therefore, we can come to the conclusion that the kneading blocks are more suitable for the melting zone of co-rotating twin screw extruders.