This paper proposes a perfect metamaterial absorber based on a dielectric−dielectric−metal structure, which realizes ultra-narrowband dual-band absorption in the near-infrared band. The maximum Q factor is 484. The physical mechanism that causes resonance is hybrid coupling between magnetic polaritons resonance and plasmon resonance. At the same time, the research results show that the intensity of magnetic polaritons resonance is much greater than the intensity of the plasmon resonance. By changing the structural parameters and the incident angle of the light source, it is proven that the absorber is tunable, and the working angle tolerance is 15°. In addition, the sensitivity and figure of merit when used as a refractive index sensor are also analyzed. This design provides a new idea for the design of high-Q optical devices, which can be applied to photon detection, spectral sensing, and other high-Q multispectral fields.