ZnS:Co　thin　films　were　grown　on　quartz　substrates　at　different　substrate　temperatures.　Evolutions　of　the　films’　microstructure　and　optical　properties　as　a　function　of　substrate　temperature　were　analyzed.　The　crystalline　quality　was　promoted,　and　the　films　demonstrated　increasing　(111)　preferred　orientation　with　increasing　substrate　temperature.　The　band　gap　decreased　when　the　substrate　temperature　was　increased　from　25℃　to　400℃,　and　then　further　increased　to　800℃.　The　evolution　of　the　band　gap　is　associated　with　the　quantum　confinement　effect.　Moreover,　the　refractive　index,　extinction　coefficient　and　dielectric　constant　of　the　films　present　an　increasing　tendency　with　the　increase　of　substrate　temperature.　It　is　shown　that　superior　microcrystal　films　can　be　obtained　at　temperatures　higher　than　400℃.　©　2023　Science　Press.　All　rights　reserved.