(1 − x)Li0.02(K0.48Na0.53)0.98(Nb0.8Ta0.2)O3–xAgSbO3 (abbreviated as LKNNT–xAS, 0.045 < x < 0.055) lead-free ceramics with a high relative density (~95 %) were successfully fabricated by the conventional method. Only a small AgSbO3 composition interval of 0.25 mol% was implemented for the purpose of property enhancement via the precise phase control. Room temperature XRD patterns confirmed that two phase coexistent structure of orthorhombic and tetragonal phases was obtained and the volume fraction of orthorhombic phase decreased as AgSbO3 increased from 0.045 to 0.055. A relatively high d33 value up to 289 pC/N was achieved in the LKNNT–0.0525AS ceramics. Meanwhile the planar electromechanical coupling factor kp, the remnant polarization Pr and the relative dielectric constant εr reached 0.42, 16.3 μC/cm2, 1967, respectively. Considering the electrical properties, AgSbO3 modified (Li,K,Na)(Nb,Ta)O3 ceramics may be a potential candidate of lead-free piezoelectric ceramics.