In this study,we consider two processing methods of graphene thin layers in plasmonic nano-optical waveguides analyzed by the finite element calculation. More specifically,we employ surface current and thin layer methods. We obtain the field distributions and effective mode indices of the fundamental modes in planar and curved graphene waveguides for different frequencies and geometric parameters. The simulation results show that both methods can efficiently tackle the problems in question. In particular, the difference between the surface current methods and the theoretical calculation results is less than 1%, and this method saves computing resources. Our results can be used to simplify the processing of graphene layers in finite element calculations and improve calculation efficiency.