Abstract: As an efficient flocculant, polyacrylamide (PAM) is widely used in water treatment process. The acrylamide monomer (AM) produced by depolymerization of residual PAM has been listed as a class IIA carcinogen, and its treatment is imminent. Flotation tailing (TC) was used as raw material to prepare a modified tailing matrix by alkali excitation. Nano-TiO₂ was loaded onto the modified tailing matrix by hydrothermal method to prepare tailing-based nano-TiO₂ composite (TiO₂/TC) and Pb-doped tailing-based nano-TiO₂ composite (Pb-TiO₂/TC). The photocatalytic degradation properties of TC, modified coal matrix, TiO₂/TC and Pb-TiO₂/TC were analyzed with PAM as the target pollutant. The samples were characterized by XRD, SEM, UV-vis and BET, and the degradation products were analyzed and studied by high performance liquid chromatography-mass spectrometry. The degradation mechanism of PAM was explored. The results show that TC is irregular and the surface is rough; the surface of TiO₂/TC is loose, the pore structure is obvious, and the fine tubular TiO₂ is uniformly coated on the surface of modified tailings. The structure of Pb-TiO₂/TC is more fluffy, and the modified coal matrix is loaded with more tubular TiO₂. The band gap of TiO₂/TC was 3.16 eV, and Pb²⁺ doping reduced the band gap of Pb-TiO₂/TC to 3.08 eV. The specific surface area of TiO₂ is 286.66 m²/g, the specific surface area of TiO₂/TC and Pb-TiO₂/TC are 360.33 m²/g and 358.54 m²/g. The higher specific surface area provides more active sites for the reaction, and the adsorption-catalytic synergistic effect significantly improves the photocatalytic efficiency. The degradation rates of PAM by TC and modified tailing matrix were 3.39% and 4.68%. The degradation rates of polyacrylamide by TiO₂/TC and Pb-TiO₂/TC loaded with TiO₂ increased to 38.92% and 63.87%. After five cycles, the photocatalytic properties of TiO₂/TC and Pb-TiO₂/TC remained basically unchanged. In the degradation process of PAM, the macromolecular PAM breaks into small molecular weight PAM molecules, and further decomposes into NO₃⁻, acrylic acid, acetamide and acetic acid.