A simple and efficient auxiliary-difference-equation finite-difference time-domain (ADE-FDTD) method for modelling graphene-based structures is presented in this paper. By considering the graphene sheet as a polarization current source characterized by an auxiliary equation (AE), the proposed method can be easily adopted to simulate graphene-based structures biased by electrostatic or magnetostatic field, respectively. The accuracy of proposed method is verified in comparison with the analytical results.