A metamaterial absorber based on vanadium dioxide(VO2) is presented. This structure consists of three layers including two vanadium dioxide circles, intermediate dielectric layer, and metal substrate from top to bottom. The simulated data shows that the absorber has two strong absorption peaks, at 4.96 THz and 5.64 THz respectively, and the corresponding absorption rates reach 99.1% and 98.5%. The physical mechanism of absorption is clarified by using the impedance matching theory and the electric field distribution. The effect of the structural parameters on the absorption rate is also analyzed. In addition, the proposed absorber can regulate the absorption rate flexibly, which provides a good scheme for the realization of terahertz wave regulation, filtering and other functions. Therefore, this absorber has potential applications in image processing, biological detection, and wireless communication.