A series of plasmonic Ag-TiO₂/H₃PW₁₂O₄₀ composite films were fabricated and immobilized by validated preparation technique. The chemical composition and phase, optical, SPR effect and pore-structure properties together with the morphology of as-prepared composite film are well-characterized. The multi-synergies of as-prepared composite films were gained by combined action of electron-capture action via H₃PW₁₂O₄₀, visible-response induced by Ag, and Schottky-junction formed between TiO₂-Ag. Under simulated sunlight, the maximal K _app of o-chlorophenol (o-CP) reached 0.0075 min⁻¹ which was 3.95-fold larger than that of TiO₂ film, while it was restrained obviously under acid condition. In the photocatalytic degradation process, ·OH and ·O₂⁻ attacked preferentially ortho and para position of o-CP molecule, and accordingly the specific degradation pathways were speculated. The novel composite film exhibited an excellent applicability due to self-regeneration of H₃PW₁₂O₄₀, well-protection of metal Ag° and favorable immobilization.