The　paper　investigated　the　effect　of　the　process　parameters,　such　as　chamber　pressure,　substrate　temperature　and　deposition　rate,　on　the　optical　characteristics　of　electron　beam　evaporation　deposited　amorphous　silicon　optical　film.　It　was　found　that　the　refractive　index　and　extinction　coefficient　of　the　film　increased　with　the　increase　of　the　vacuum,　substrate　and　deposition　rate　in　the　wavelength　range　of　300-1100　nm.　The　results　were　applied　to　the　deposition　of　high　reflection　mirror　of　semiconductor,　and　the　refractive　index　of　3.1　and　extinction　coefficient　of　1E-3　at　808　nm,　were　obtained　with　the　base　vacuum　of　1E-6　×　133　Pa,　the　temperature　of　100°C　and　the　deposition　rate　of　0.2　nm.