Abstract: This paper applies the dispersive hybrid implicit-explicit finite-difference time-domain method (HIE-FDTD) to analyze the electromagnetic properties of graphene. The time step size of this method is not limited by the mesh size of the graphene layer. Numerical examples show that the HIE-FDTD method is an efficient algorithm with high precision, and its calculation time is greatly reduced compared to the FDTD scheme.The numerical calculation result shows that the designed graphene absorber can effectively adjust the absorption peak of the absorber by changing the chemical potential of the graphene sheet with using the HIE-FDTD method. The absorption rate of graphene absorber at terahertz frequency shows a certain periodicity and exhibits grid-like characteristics, and this feature can provide some ideas for the design and production of graphene devices.