Abstract: Coal-fired power (FMH) generation dominates the current energy landscape, but it generates fly ash as a by-product of power generation not only takes up land, but also may cause dust and pollution. Concurrently, substantial CO₂ emissions from the greenhouse effect are exacerbating. Carbon capture and storage (CCS) technology is one of the effective solutions to mitigate the greenhouse effect. Metal-organic frameworks (MOFs) have great potential for CO₂ capture due to their controllable porous structure and high specific surface area. In this study, MOFs@FMH composites were synthesized via a solution method using fly ash and waste polyethylene terephthalate (PET) as raw materials, and characterized by XRD, SEM, FTIR, TGA and N₂ physisorption (BET). The results demonstrate that the porous architecture of fly ash facilitates the outward growth or surface loading of MOFs crystals. 25%Fe-MOF@FMH composite has good crystallinity, complete crystal structure, specific surface area and micropore volume of 104.5 m²/g and 0.078 cm³/g, which are 48 times and 52 times those of fly ash, respectively. Under identical atmospheric pressure conditions, 25%Fe-MOF@FMH composite exhibited the highest CO₂ adsorption capacity among the synthesized series, reaching 1.48 mmol/g at 25℃ and 0.91 mmol/g at 80℃, respectively. The CO₂ adsorption capacity showed a trend of first increasing and then decreasing with increasing Fe-MOF loading. This non-monotonic trend is primarily attributed to the evolution of pore structure: An optimal loading facilitates the formation of abundant and well-defined micropores, maximizing accessible adsorption sites, whereas insufficient loading results in limited active sites, and excessive loading induces pore blockage and structural disorder, both of which are detrimental to adsorption performance.