Based on patterned graphene, an ultra-thin broadband terahertz metamaterial absorber with the thickness of 33.254 μm (about 1/7 of the incident wavelength) is designed. The bandwidth with an absorptivity of above 80% can reach 1.422 THz. The simulation and analysis results show that the absorption characteristics of this absorber is polarization-independent and insensitive to the incident angle. The absorbed energy of this absorber can be adjusted effectively by changing the chemical potential of graphene. In addition, the absorption performance can be improved when the thickness of polyimide interlayer increases.