CuO　powder　with　microspheres,　submicron　sheets　had　been　synthesized　only　from　CuSO4　and　Na2CO3　aqueous　solutions　by　a　facile　route.　Significant　effects　of　initial　droplet　size　of　CuSO4　aqueous　solution　were　observed　on　particle　size,　morphology　and　gas　sensitivity　of　CuO.　The　morphologies　of　CuO　powder　varied　from　microspheres　to　submicron　sheets　with　the　introduction　method　of　CuSO4　to　Na2CO3　aqueous　solutions.　Based　on　the　characterized　structure　and　morphology,　a　possible　formation　mechanism　of　CuO　had　been　proposed.　High　gas　sensitivity　to　ethanol　was　obtained　for　the　CuO　microspheres　synthesized　by　spray　method,　which　exhibited　the　response　sensitivity　of　3.25　to　ethanol　with　the　concentration　of　300　ppm　at　250　degrees　C.　It　suggests　that　the　facile　route　is　promising　to　the　batch　synthesis　of　CuO　powder　with　good　gas　sensing　properties.