Lead-free 0.98(K0.5Na0.5)NbO3-0.02(Ba0.6Sr0.4)(0.7) Bi0.2TiO3 (abbreviated as 0.98KNN-0.02BSBT) ceramics were prepared by the conventional solid-state sintering method. Effect of sintering temperature on 0.98KNN-0.02BSBT ceramics was systematically investigated. The frequency dependent dielectric permittivities show that the ceramics sintered at different temperatures are indeed "relaxor- like'' ferroelectric ceramics, which possess a diffuse phase transition without a strong frequency dispersion of dielectric permittivity. The diffuseness parameter gamma, the comparison of the relaxor behavior based on empirical parameters (Delta T-diffuse) and the slimmer P-E hysteresis loops confirm that the "relaxor- like'' characteristics of the ceramics are strengthened with increasing sintering temperature. At the optimum sintering temperature, the dielectric permittivity maximum (epsilon(max)) has a value of approximately 2795 (at 1 KHz), tan delta is lower than 2.5 % and the diffuseness parameter gamma = 1.68 at a broad usage temperature range (150-350 degrees C), which indicate its potential application in high temperature multilayer ceramics capacitor field.