Modeling targets with infinitely thin graphene sheets by using the finite-difference time - domain (FDTD) poses a challenge, arising from the presence of surface currents and the difficulty in implementing longitudinal discretization. When analyzing the electromagnetic properties of targets via the FDTD method, spatial discretization of the target is essential. In the case of macroscopic electromagnetic targets that combine ‘infinitely thin’ graphene interfaces, this interface cannot be longitudinally partitioned. Moreover, a surface current exists at the interface, rendering the traditional calculation methods for the tangential electric field on the interface inapplicable. To address this issue, we put forward a novel equivalent source current (ESC) approach. The proposed method enables the graphene sheet to retain a two - dimensional structure and be positioned on the surface of the Yee cell during the spatial discretization of the FDTD method(Fig.1). Subsequently, the surface current on the graphene sheet is approximated as a source volume current. Then, the active Maxwell's equations are discretized at the tangential electric - field nodes on the graphene surface(Figs. 1 and 2), thereby obtaining a modified formula for the electric - field. By introducing intermediate variables and using the shift operator (SO) method, which is employed to handle the issues related to dispersive media and to process the correction formula, an FDTD iterative formula for calculating the tangential electric field at the graphene interface is derived. This ultimately enables the FDTD calculations for targets with ‘infinitely thin’ graphene sheets. Excellent agreement between our FDTD results and analytical solutions in several numerical examples validates the proposed method. The methodological framework proposed in this study can be generalized and applied to the ‘zero-thickness’ dispersive interfaces featuring surface current distributions, such as metallic films and two-dimensional transition metal sulfides. This enables convenient numerical analysis of the electromagnetic properties of structures that include conductive dispersive interfaces.