© 2022 Elsevier B.V.Thermal transport in the Metal Oxide Semiconductor Field Effect Transistor (MOSFET) has received increased attention across a number of disciplines in recent years. One of the most significant current discussions in this problem is the efficiency decrement of MOSFET due to its nanoscale size and self-heating. Graphene transistors based on carbon material present a modern technology for future manufacturing of nano-electronic devices. This paper assesses the significance of the specularity parameter on phonon heat transport within nanoscale graphene transistor using a Lattice Boltzmann Method with D2Q8 model. The suggested work has been proved by available results from previous studies. The current study found that the interface temperature were 323.2 K and 305.7 K for the silicon-transistor and graphene-transistor, respectively. The obtained results indicate that the specularity parameter has an important role in the phonon heat transport and in the reducing of the maximal temperature in the graphene nanoribbon MOSFET. The findings of this investigation show that the transistor based on organic carbon (graphene) is thermally more stable than the conventional silicon transistor.