Effects of K5.4Cu1.3Ta10O29 (KCT) doping on structural and electrical properties of 0.05mol% Ni2O3 modified [(K0.43Na0.57)0.94Li0.06][(Nb0.94Sb0.06)0.95Ta0.05]O3 (KNLNST) ceramics have been studied. It is found that the addition of suitable amount KCT can significantly enhance Qm and suppress tanδ while virtually maintaining d33 of the ceramics. The 0.2mol% KCT added KNLNST +0.05mol% Ni2O3 ceramic shows a high Qm (~180) and a very low tanδ (0.82%), which are respectively nearly four times and a quarter of those of pure KNLNST +0.05mol% Ni2O3 ceramic. Meanwhile, d33 and kp of this ceramic maintain relatively high values (d33=287 pC/N, kp=46.2%). The dramatic change of Qm (tanδ) and virtual maintenance of d33 (kp) are mainly attributed to the effects of Cu2+ and K+ in KCT, respectively. High Qm and d33 but remarkably low tanδ indicates large potential of this ceramic for making high power transducer devices.