Lead-free piezoelectric ceramics (1 - x) (Na0.53 K0.404 Li0.066) Nb0.92 Sb0.08 O3 + x SrTiO3 are fabricated by conven-tional solid-state sintering method, and their dielectric and piezoelectric characteristics are investigated. With the addition of SrTiO3, the growth of the grain size is restrained, meanwhile the phase transition temperature of orthorhombic-tetragonal is shifted below room temperature. It is found that the ceramics with x = 0.010 exhibit excellent piezoelectric properties (d33=220 pC/N, kp = 41%, kt=39%) and improved thermal stability around room temperature. The results indicate that these materials are promising lead-free piezoceramics for practical operations.