In this study,Ag-TiO_2films were fabricated by electron beam evap oration.The as-prepared composite Ag-TiO_2films are characterized by scanning electron micros copy (SEM),transmission electron microscope (TEM),X-ray diffraction (XRD),atomic force microscopy (AFM) and UV- Vis spectrometer to determine the morphology,phase components,absorption spectrum and roughness,respectively. With methyl orange as the model pollutant,the photocatalytic activity is studied to investigate the influ ence of film thickness on the photocatalysis under the sunlight.The research res ults indicate that the Ag-TiO_2films are amorphous at 300℃ and the degradation rate of MO reaches 55% for 40days when the film thicknes s is 570nm.