The coordination compound of Fe(Ⅲ) with 2,2-bipyridine-1,1-dioxide was synthesized,It was characterized by elemental analysis,IR,UV and molar conductivity.The gas sensitive property was studied,the results indicated that the composition of the coordination compound is [Fe(bipyO_2)Cl_2]Cl·1/6 bipyO_2.The sensor manufactured by coordination compound has very high sensitivity and selectivity to ammonia.It could be used in ammonia leak-alarm and in environment realtime supervising ammonia.