In　the　present　study,　high　quality　rubrene　thin　film　is　fabricated　through　control　of　growth　time　with　thermally　evaporation　under　vacuum.　Optical　microscopy　is　employed　to　analyze　the　surface　morphology　of　the　samples.　A　mode　of　thin　film　growth　from　an　amorphous　continuous　film　to　polycrystalline　rubrene　thin　film　could　be　controlled　by　growth　time.　Images　of　such　structures　[acquired　using　optical　microscopy]　show　that　they　are　polycrystalline　structure,　which　splays　out　from　a　central　point.　Rubrene　thin　film　is　linear　structure　when　the　growth　time　is　greater　than　7　hours.　Meanwhile,　the　optical　constant　(absorption　coefficient　(α))　is　analyzed　by　transmission　and　absorption　spectrum.　The　optical　band　gap　(Eg)　is　deduced　by　Tauc　formula.　From　the　ultraviolet　absorption　spectrum　of　rubrene　thin　film,　we　observe　two　shape　peaks,　which　can　be　explained　by　Davydov　splitting　(factor-group　splitting).　©　2009　SPIE.