A　novel　hybrid　structure　sensor　based　on　cobalt　carbonate　hydroxide　hydrate　(CCHH)　and　reduced　graphene　oxide　(RGO)　was　designed　for　room　temperature　NH₃　detection.　This　hybrid　structure　consisted　of　CCHH　and　RGO　(synthesized　by　a　one-step　hydrothermal　method),　in　which　RGO　uniformly　dispersed　in　CCHH,　being　used　as　the　gas　sensing　film.　The　resistivity　of　the　hybrid　structure　was　highly　sensitive　to　the　changes　on　NH₃　concentration.　CCHH　in　the　hybrid　structure　was　the　sensing　material　and　RGO　was　the　conductive　channel　material.　The　hybrid　structure　could　improve　signal-to-noise　ratio　(SNR)　and　the　sensitivity　by　obtaining　the　optimal　mass　proportion　of　RGO,　since　the　proportion　of　RGO　was　directly　related　to　sensitivity.　The　gas　sensor　with　0.4　wt%　RGO　showed　the　highest　gas　sensing　response　reach　to　9%　to　1　ppm　NH₃.　Compared　to　a　conventional　gas　sensor,　the　proposed　sensor　not　only　showed　high　gas　sensing　response　at　room　temperature　but　also　was　easy　to　achieve　large-scale　production　due　to　the　good　stability　and　simple　synthesis　process.