Abstract: In order to improve the photocatalytic performance of TiO₂ under visible light, a highly ordered β-FeOOH/TiO₂ composite film material was prepared on FTO conductive glass through a secondary hydrothermal reaction, using scanning electron microscopy (SEM) and X-ray diffraction (XRD), Raman (Raman) and infrared spectroscopy (FTIR) analyzed its surface morphology, crystal structure and phase composition. UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS) was used to test its light absorption performance. Finally, using methyl orange (MO) as a simulated pollutant, the photocatalytic activity of the composite film material under visible light was investigated. The results show that: TiO₂ and β-FeOOH are connected by Fe—O—Ti bond, and the β-FeOOH/TiO₂ composite film material successfully prepared has good structural stability. The β-FeOOH/TiO₂ composite film material, due to its structural heterojunction and suitable energy band structure, effectively improves the migration efficiency of photogenerated carriers, and successfully expands its photoresponse range to about 540 nm. The composite film material exhibits excellent photocatalytic performance under visible light. The photocatalytic efficiency of β-FeOOH/TiO₂ is 60.6% higher than that of the unmodified TiO₂ sample. After six photocatalytic degradation cycles, the composite film is still in good condition. The continuity of the photocatalytic degradation of MO is still maintained at about 94%.