Abstract: To recognize the variation of SiO2 films irradiated by the laser, SiO2 films were prepared by electron beam evaporating on K9 substrates in the same experimental conditions with the exception that the irradiating laser energy was different in order to investigate the effects on the film-s transmittance, refractive index, extinction coefficient, film thickness, surface morphology and laser-induced damage threshold (LIDT) .The result shows that irradiating laser can decrease the SiO2 films- thickness , and improve the surface roughness of films. Finally, the result means that irradiation can increase the LIDT of films from 16.96 J/cm2 to 18.8 J/cm2.