ZnSe:Co　thin　films　were　grown　on　sapphire　(Al2O3)　substrates　by　pulsed　laser　deposition　at　different　substrate　temperature.　Evolutions　of　the　microstructure,　morphology　and　optical　properties　of　the　ZnSe:Co　thin　films　as　a　function　of　substrate　temperature　were　analyzed.　The　results　indicated　that　the　crystalline　quality　was　promoted　and　the　films　demonstrated　increasing　(111)　preferred　orientation　with　increasing　substrate　temperature.　Excellent　crystalline　quality　and　(111)　preferred　oriented　thin　film　was　grown　at　substrate　temperature　of　800　degrees　C.　The　refractive　index　and　dielectric　constant　analyzed　by　the　transmission　spectra　increased　with　elevating　substrate　temperature,　which　may　be　due　to　the　promotion　of　the　film　packing　density.　The　thin　films　with　wider　optical　band　gap　in　range　of　2.73　eV　to　3.27　eV　were　obtained　in　the　experiment.　The　band　gap　decreased　when　the　substrate　temperature　was　increased　from　25　degrees　C　to　600　degrees　C,　and　then　increased　with　a　further　increase　of　substrate　temperature　to　800　degrees　C.　The　evolution　of　band　gap　associates　with　the　quantum　confinement　effect.