In this paper, the influence of annealing temperature on the structure and optical properties of silicon films was systemically investigated. Silicon films were deposited by electron beam evaporation and then annealed in N₂ atmosphere within a temperature range from 200 to 500 °C. The films were characterized by X-ray diffraction （XRD）, Raman spectroscopy, electronic-spin resonance （ESR） and optical transmittance measurement, respectively. With annealing temperature increased, the amorphous network order of silicon films was improved on the short and medium range and the defect density decreased remarkably. When sample being annealed at 400°C, the extinction coefficient k decreased from 6.14×10^-3 to a minimum value of 1.02×10^-3 （at 1000 nm）, which was due to the lowest defect density, about one fifth of the as-deposited sample. The results showed that annealing at an appropriate temperature could effectively reduce the optical absorption of silicon films in the near infrared region, which were very critical for the application in optical thin film coating devices.