A multiband tunable metamaterial terahertz absorber based on VO₂ material is introduced and studied. The absorber consists of gold planes and periodic metallic materials. The first layer is gold plane, the second layer is polyimide, the third layer is silicon film, and the fourth layer is super surface. From the simulation results, we can see that the phase transition occurs when the temperature of VO₂ is greater than or equal to 68°C. After the phase transition, there are three absorption peaks, and the absorption rates are more than 99% at 2.53, 5.7, and 8.67 THz, realizing perfect absorption. When the temperature of VO₂ is less than 68°C, the maximum absorption rate is 30.4%, which fails to meet the absorption requirements. By increasing the thickness of polyimide, the absorption spectrum moves slightly to the low frequency band to achieve redshift. Compared with most of the proposed multiband absorbers, the metamaterial absorber with adjustable absorption spectrum has better application prospects. VO₂ is a phase change material with insulator metal phase transition characteristics and reversible process. By using the phase transition characteristics of VO₂, the absorber has a switching function and is conducive to the flexible regulation of the absorption spectrum.