Abstract: Addressing the coupled challenges posed by the complexity of geological conditions in coal mining subsidence areas and the demand for lightweight construction, this study focuses on prefabricated building wall systems. It concentrates on the collaborative optimization mechanism of lightweight low-carbon materials and structures, aiming to establish a scientific selection method for wall insulation materials that balances lightweight and low-carbon considerations in special geological environments. A parametric numerical simulation is established to systematically compare six types of insulation materials. A multi-dimensional evaluation system is constructed to conduct quantitative analysis from key indicators such as areal density, embodied carbon, operational embodied carbon, and economy, dividing material selection strategies into "lightweight priority" and "low-carbon priority". The research findings indicate that EPS and polyurethane excel in lightweight performance, with areal densities controllable within 7 kg/m², with EPS exhibiting the best areal density index. XPS and STP are the two materials with the best low-carbon performance, offering a wider range of suitable wall insulation thicknesses under the architectural design requirement of total carbon emissions below 170 tCO₂. When setting thresholds for wall areal density and carbon emissions, STP is preferred for ultra-thin insulation materials, with its optimal balance point between lightweight and low-carbon corresponding to a thickness of 26 mm; polyurethane is preferred for conventional thickness insulation materials, with its optimal balance point corresponding to a thickness of 150 mm. Both can achieve the optimal balance between lightweight and low-carbon. In engineering scenarios with economic constraints, EPS is recommended as the wall insulation material; STP, due to its high cost, has a limited application range, but its excellent insulation performance makes it an ideal alternative for wall insulation in ultra-low energy consumption buildings. The multi-dimensional evaluation method and material selection strategy proposed in this study provide a scientific basis for the selection of wall insulation materials for prefabricated buildings in cold regions with coal mining subsidence areas.