To realize the dynamic adjustable function of the broadband absorber, this paper proposes and designs a symmetrical absorber structure composed of a square top layer with embedded cross, a SiO₂ dielectric layer, and a VO₂ bottom layer. In the range from 2 THz to 4 THz, the absorption efficiency of the device can be adjusted from less than 10% to more than 90% by adjusting the conductivity of the bottom layer of VO₂, and its switching modulation depth is greater than 65%. In a wide frequency range, the device can be dynamically switched between the reflector and perfect absorber modes. The simulation results show that the absorber has wide-angle and polarization-insensitive characteristics, and the incident angle range of electromagnetic waves to the absorber can reach 75°. Based on the above advantages, the absorber has great potential in terahertz device applications such as smart attenuators, reflectors, and spatial modulators.