Ba(Zn1/3Ta2/3)O3 (BZT) ceramic has 1:2 ordered hexagonal structure, but was destroyed with the addition of ZrO2. The 1:1 ordered cubic structure was developed when a large amount of ZrO2 was added. BZT has a porous and inhomogeneous microstructure with a Ba5Ta4O15 second phase. When ZrO2 was added, a new Ba0.5TaO3 second phase formed and grain growth occurred. Presence of liquid phase which is related to the Ba0.5TaO3 second phase could be responsible for the grain growth. Q value of BZT was greatly enhanced with the addition of ZrO2. The improvement of Q value can be explained by the increase of relative density and grain size. Especially, grain size is considered to be one of the crucial factors for the improvement of Q value of BZT ceramic.