In this study, KNbO3-substituted (Li,Na,K)(Nb,Sb,Ta)O3 ceramics were investigated to develop Pb-free composition ceramics for multilayer actuator and energy harvester applications. The X-ray diffraction analysis indicated that all samples were pure perovskite phase and no secondary phase was found. A tetragonality as a function of KNbO3 substitution showed the maximum value at 1.5 mol% KNbO3 and then decreased. The SEM image analysis showed the maximum grain size of 3.14 ㎛ at 1.5mol% KNbO3. In the composition ceramics with 1.5 mol% KNbO3 sintered at 1,100℃, excellent properties of density= 4.75 g/cm3, electromechanical coupling factor (kp)= 0.50 and piezoelectric constant(d33)= 290 pC/N were obtained, respectively, suitable for piezoelectric actuator and energy harvester applications.