The finite - difference time - domain (FDTD) modeling of targets with infinitely thin graphene sheets poses a challenge due to the existence of surface current and the inability of longitudinal discretization. When analyzing the electromagnetic properties of targets via FDTD method, spatial discretization of the target is essential. In the case of macroscopic electromagnetic targets that incorporate ‘infinitely thin’ graphene interfaces, this interface cannot be longitudinally partitioned. Moreover, a surface current exists on the interface, rendering the conventional 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.2). 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(Fig.2, Fig.3), thereby obtaining a modified formula for the electric - field. By introducing intermediate variables and integrating the Shift Operator (SO) method, which is employed to handle issues related to dispersive media, to process the correction formula, an FDTD iterative formula for calculating the tangential electric field at the graphene interface is deduced. 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 with surface current distributions (such as metallic films and two-dimensional transition metal sulfides). This allows for a convenient numerical analysis of the electromagnetic properties of structures incorporating conductive dispersive interfaces.