Well dispersed CeO₂ nanoparticles are prepared by azeotropic co-precipitation method. (Ba0.96Ca0.04)(Ti0.90Sn0.10)O₃ lead-free piezoelectric ceramics doped with nano-CeO₂ (x =0 mol%, 0.03 mol%, and 0.07 mol%) and micro-CeO₂ (x = 0.03 mol%) are prepared at 1430 °C for 2 h by the conventional solid state sintering method. XRD diffraction indicates that all components have typical perovskite structure. Both doping of nano-CeO₂ and micro-CeO₂ can inhibit grain growth. And the average grain size decreased apparently with the increase of nano-CeO₂ amount. All the samples exhibit typical diffuse phase transition behavior. The optimized electrical performances are obtained at x = 0.03 mol% with d33 = 512 pC/N, kp = 41.5%, and Pr = 14.00 μC/cm².