Ba3(Ca1.18Nb1.82)O9-d (BCN18) powder was synthesized using a wet chemical method from mixtures of all water-soluble compounds including Ba, Ca and Nb-citrate. It has been found that NH4NO3 in the initial solutions plays an important role in controlling the enthalpy of low temperature combustion process as well as the gel decomposition temperature. Further steps include evaporating, drying and calcinating. The obtained gels were characterized by TG-DSC, and the powder was characterized with XRD, TEM and BET. The experimental results have indicated that the heating temperature was only 800°C for synthesizing the powder and the average particle size was only about 40-50 nm. Furthermore it was found that a pure BCN18 phase with complexperovskite structure was formed at 800°C, which was about 800°C lower than that of the traditional solid-reaction method. So it is more practical and more superior to the traditional solid-reaction method and the present wet-chemical method in alcohol salt system reported in literature.