© 2016 Trans Tech Publications, Switzerland. The effect of particle sizes of CaZrO 3 (CZ) nanocrystal on the phase structure, microstructure and electrical properties of Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT) was studied. CaCO 3 and ZrO 2 were used as starting materials for CaZrO 3 (CZ) seeds synthesized by the molten-salt method. The results found that CZ powder had a pure perovskite phase with particle size about 370 to 460 nm. The CZ-seed were then mixed with the metal oxides BaCO 3 , CaCO 3 , ZrO 2 and TiO 2 by the mixed oxide method. The phase structure, microstructure and electrical properties of BCZT ceramic were investigated as a function of particle size and concentration of CZ. The results indicated that all samples showed pure perovskite phase. The highest values of density, grain size, dielectric constant (ϵ r ) and piezoelectric coefficient (d 33 ) were 5.50 g/cm 3 , 10.95 μm, 2992 and 446 pC/N, respectively which were obtained for the BCZT ceramic doped with CZ-seed particle size of 459 nm.