A three-dimensional (3D) finite element model was created to simulate the friction stir welding process of 6063-T5 aluminum alloy. The analysis studies the fundamental knowledge of FSW process with respect to temperature difference in material to be joined and to simulate the temperature distribution in the workpiece as a result of a Friction Stir Welding. The simulation uses HyperMesh and HyperView solver from Altair Hyperworks. The simulation provides better understanding for the peak temperature distribution in the friction stir process. Two cases have (i) constant traverse speed, but varying been simulated rotational speed, and (ii) constant rotational speed, but varying traverse speeds. Simulation results show the peak temperatures increased when the traverse and rotational speeds were increased.