The high-power properties of (Sr,Ca)2NaNb5O15 (SCNN) lead-free piezoelectric ceramics were investigated in a longitudinal mode using their rectangular column modified electrode patterns. It was hard to rise the SCNN temperature with increasing vibration velocity and we were able to drive with about a two times higher vibration velocity than that of hard-PZT. The quality factor of SCNN gradually decreased with the vibration velocity and increased with the temperature. The equivalent stiffness of SCNN was almost constant with increasing strain and there was no mechanical nonlinearity, however those of hard-PZT decreased significantly with vibration velocity and strain for the softening effect as mechanical nonlinearity. SCNN has also a positive temperature dependence of quality factor and equivalent stiffness similar in a radial vibration mode. It was clarified that the high-power properties of SCNN in a longitudinal mode had superior performance such as that of the radial vibration mode.