This study presents a tunable terahertz （THz） absorber based on VO₂ and graphene as well as the validation of its performance through CST simulations. The device integrates the insulator-to-metal phase transition characteristics of VO₂ with the electrically tunable properties of graphene， enabling controllable switching between the broadband-narrowband and dual-broadband absorption modes. Simulation results demonstrated that in the metallic state， VO₂ achieved over 90% broadband absorption within the range of 3. 61-7. 43 THz， whereas in the insulating state， it exhibited four narrowband absorption peaks at 6. 4，7. 35，8. 29， and 9. 20 THz， each with a peak absorption rate exceeding 90%. By adjusting the Fermi level of graphene （0-0. 7 eV）， the absorption characteristics can be dynamically modulated： in the metallic state， the absorption band shifts from low frequency （3. 61-7. 43 THz） to high frequency （6. 88-8. 99 THz）； in the insulating state， a transition from four-narrowband mode to quasi-singlenarrowband mode can be achieved. Owing to its structural symmetry， the device exhibits excellent polarization insensitivity and wide-angle stability， demonstrating significant application potential in terahertz switching， electromagnetic shielding， stealth technology， and sensors.