Abstract: (Na_0.51K_0.44Li_0.05)Nb_0.92Ta_0.08O₃ and sintering aid Na_5.4Cu_1.3Sb₁₀O₂₉ were prepared by conventional oxide solid solution technique.It is shown that the effects of Na_5.4Cu_1.3Sb₁₀O₂₉ on improving the piezoelectric and electromechanical coupling property of（Na_0.51K_0.44Li_0.05）Nb_0.92Ta_0.08O₃ are very remarkable.（Na_0.51K_0.44Li_0.05）Nb_0.92Ta_0.08O₃ doped with 4wt% Na_5.4Cu_1.3Sb₁₀O₂₉ has higher piezoelectric constant（d₃₃=266pC/N）,higher electromechanical coupling constant kt（46.7%）、k₃₃（63.7%）,a small loss（tanδ=1.8%）at 1kHz,high Curie temperature,Tc（391℃）.These data show that Na_5.4Cu_1.3Sb₁₀O₂₉ doped（Na_0.51K_0.44Li_0.05）Nb_0.92Ta_0.08O₃ are very promising as practicable lead-free piezoelectric ceramics replacing lead zirconate titanate.