The infrared spectrum (0.78–30 μm) plays a vital role in materials detection, energy harvesting, environmental sensing, and national defense security. However, traditional materials, limited by the strong coupling between intrinsic optical constants and thermal properties, struggle to achieve independent and precise tailoring of the infrared spectrum. Recently, the emergence of hierarchical photothermal metamaterials has provided a novel paradigm to address this challenge. This paper explores a multi-dimensional, multi-physics cross-band infrared spectral modulation mechanism based on micro-nano structure design, focusing on the evolution from microscopic electromagnetic resonance to macroscopic spectral and thermal field management. It reviews the progress of photothermal metamaterials in constructing ideal blackbodies and achieving infrared camouflage, and delves into their breakthroughs in energy applications such as radiative cooling and thermophotovoltaics. Finally, we outline the challenges and opportunities facing this field in both theoretical research and engineering applications, including large-area manufacturing processes and adaptability to extreme environments.