Abstract: The far-infrared band has potential applications in fields such as infrared stealth and thermal imaging. Based on the characteristics of multi-morphology stacked structures, a broadband metamaterial absorber covering the far-infrared spectrum was designed. The absorber structure is composed of double-layered Ti-Si₃N₄ star-shaped and double-layered Ti-Si₃N₄ rectangular units. The finite-difference time-domain method was used to analyze the absorption characteristics and the mechanism of the absorber. The research results show that the designed absorber exhibits excellent absorption characteristics in the far-infrared band (6-17 μm), with an absorption bandwidth of 10.24 μm calculated at an absorption exceeding 90%. The absorber not only has significant polarization insensitivity but also maintains average absorption of 91% and 75% under 60° oblique incidence in TM and TE modes, respectively, demonstrating certain wide-angle absorption characteristics. Mechanistic analysis reveals that the high absorption and broadband characteristics of the absorber are attributed to the synergistic effects of surface plasmon resonance, localized surface plasmon resonance, and propagating surface plasmon resonance. The excellent absorption characteristics of the designed absorber hold certain potential application value in thermal imaging, sensing technology, infrared stealth, and other aspects.