In　recent　years,　chalcogenide　glasses　such　as　ZnS　or　ZnSe　have　attracted　much　attention　due　to　their　excellent　optical　properties.　The　structure　of　chalcogenide　materials　is　part　of　the　important　factors　affecting　their　optical　properties.　In　this　paper,　the　magnetic　environment　was　set　to　control　the　growth　structure　of　nano　film　in　the　process　of　deposition,　which　could　be　affected　the　optical　properties　of　Co-doped　ZnS　(ZnS:Co)　nano-film.　All　films　were　prepared　by　pulsed　laser　deposition　(PLD).　The　results　of　XRD　and　Raman　proved　that　the　structure　of　the　film　was　changed　by　the　magnetic　field.　A　broader　band　fluorescence　characteristic　in　the　film　was　shown　by　PL　spectrum,　which　revealed　a　substantially　improvement　of　the　optical　properties　for　this　material.　Under　the　condition　of　the　magnetic　field,　consistency　between　FDTD　(Finite　difference　time　domain　method,　FDTD)　simulation　and　experimental　results　further　confirmed　the　improvement　of　the　optical　properties.　The　findings　warrant　that　the　optimized　ZnS:Co　thin　films　could　be　applied　to　develop　efficient　optical　waveguide　devices　and　laser　gain　media　in　the　infrared　field.