CuO-doped (K0.5Na0.5)Nb0.9Ta0.1O3 lead-free piezoelectric ceramics have been prepared by conventional sintering technique and the effects of CuO on the phase structure and piezoelectric properties of the ceramics have been studied. The results show that a small amount of CuO can improve the densification of the ceramics, consequently, the electric properties are improved. Good piezoelectric and dielectric properties of d33=125 pC/N,Kp=0.38,εr=700, Qm=248,and Tc=370°C were obtained for the K0.5Na0.5 Nb0.9Ta0.1O3 ceramics doped with 0.5mol% CuO sintered at 1000℃ for 2h.