Abstract: The hybrid implicit-explicit FDTD (HIE-FDTD) method is used to numerically simulate the graphene absorber. The intraband conductivity of graphene is introduced into the HIE-FDTD method through the auxiliary difference equation (ADE) and the conformal technology is used to complete the characteristic analysis of the designed new graphene absorber. Numerical results show that the absorption rate of the absorber can reach 99.8% near 2.68 THz, and the working frequency of the absorber can be adjusted by controlling the chemical potential of graphene and the width of the ring in the terahertz frequency band. The ring-shaped absorber designed in this paper has a simple structure and has potential applications in terahertz devices such as detectors, sensors, and filters.