Electromechanical properties and high power characteristics of Pb-free hard piezoelectric ceramics in the (BiNa0.88K0.08Li0.04)(0.5) (Ti1-xMnx)O-3 (x=0, 0.014, 0.015, and 0.016) system were studied. Mn doping resulted in a considerable enhancement of mechanical quality factor Q(m) and vibration velocity. The lowest mechanical and dielectric losses were achieved in 1.5mol% Mn-doped ceramics with a planar Q(m) of about 970 and tan of 0.89%. The heat dissipation and resonance frequency shift under high drive condition were remarkably suppressed upon Mn doping. The maximum vibration velocity was increased from 0.28m/s in undoped ceramic to 0.6m/s in 1.5mol% Mn-doped composition. The results of this study revealed that Mn-doped BNT-based piezoelectrics exhibited a superior high power performance compared to their lead-based counterparts such as PZT4 and PZT8 ceramics.