The electronic properties of the single and bilayer graphene have been carefully investigated by the principle of Hamiltonian tight binding model. We find that the energy band gap of bilayer graphene is tunable from 0 to 0.29 eV under the applied electric field. Using the energy band gap analysis from Hamiltonian tight-binding simulations, we also concluded that the charge distribution in inter and intra-graphene layer determine the energy band gap structure. Based on the applied mechanism, the bandgap of bilayer graphene can be engineered under DC and low amplitude electric med potential for the optical excitation. © 2018 IEEE.