We　study　the　effect　of　demand　uncertainty　on　two　classes　of　newsvendor　problems　by　using　stochastic　dominance　and　variability　orderings　in　applied　probability,　one　is　the　classical　newsvendor　problem　with　minimization　cost,　the　other　is　the　newsvendor　problem　with　maximization　profit　with　two　ordering　policy.　We　get　the　monotonicities　of　the　optimal　cost　(optimal　profit)　corresponding　to　the　two　classes　of　newsvendor　problems　with　respect　to　the　shortage　penalty　cost　(two　ordering　cost),　and　equivalence　of　the　two　classes　of　newsvendor　problems　from　the　optimization　and　stochastic　comparison＇s　point　of　view.　For　the　newsvendor　problem　with　maximization　profit,　we　provide　the　sufficient　conditions　to　compare　newsvendor＇s　optimal　profit　under　the　dispersive　ordering,　and　show　that　stochastic　larger　demand　leads　to　larger　newsvendor＇s　optimal　profit　when　two　ordering　cost　is　smaller　than　or　equal　to　sales　price,　however,　this　result　may　not　be　true　when　two　ordering　cost　is　larger　than　sales　price.　We　show　that　the　optimal　profit　will　decrease　when　demand　variability　increasing　under　the　second　degree　stochastic　dominance　for　any　two　ordering　cost,　and　there　exists　a　certain　demand　distribution,　the　optimal　profit　will　increase　when　demand　variability　increases　for　those　two　ordering　cost　that　is　larger　than　a　fixed　value.　We　obtain　similar　results　for　the　newsvendor　problem　with　minimization　cost.　Several　numerical　examples　are　provided　to　show　those　obtained　results.