The　optical　constants,　surface　structure,　thermal　and　humidity　stability　of　amorphous　silicon　optical　films　have　been　investigated　by　using　regular　electron　beam　evaporation　and　Ar　assisted　deposition.　It　is　found　that　Ar　ion　bombardment　can　enhance　the　refractive　index,　decrease　the　roughness　and　improve　the　thermal　and　humidity　stability,　and　but　it　leads　to　the　narrowing　of　the　bandgap　and　the　increase　of　the　optical　absorption.