To realize high-efficiency countermeasures and stealth for future remote terahertz radar, a wide-band terahertz absorbing structure with graphene was designed for typical operating frequencies of terahertz radar. The basic absorbing structure unit of wide-band absorbing structure was the surface metal layer/graphene layer/dielectric layer/bottom metal layer, and the dual-scale four separation layers were designed and optimized to certain the structure parameters of each layer using the genetic algorithm. Simulation results show that the absorption efficiency of wide-band absorbing structure is better than 80% in the frequency range of 0.138 THz~2 THz, 97.46% in the frequency range of 0.157 THz~2 THz, and 92.27% at the typical terahertz radar operating frequency, which satisfy the demands of countermeasures and stealth for terahertz radars.