The invention discloses a high-strain sodium bismuth titanate-based ceramic and a preparation method thereof. The stoichiometric ratio of the high-strain sodium bismuth titanate-based ceramic is as follows: 0.8(BiNa)0.5-x(LaLi)xTiO3-0.2Bi0.5K0.5TiO3; and x is equal to 0.006-0.012. The high-strain sodium bismuth titanate-based ceramic and the preparation method disclosed by the invention have the advantages that by optimization of a ceramic formula, the environmental-friendly type lead-free piezoelectric sodium bismuth titanate-based ceramic has high strain under a lower electric field after the processes of mixing, ball milling, low-temperature presintering and high sintering; and when the electric field at room temperature is 45kV/cm, the strain reaches 0.387%, the dynamic piezoelectric constant d33* reaches 860pm/V, and simultaneously the material maintains excellent fatigue resistance under 106 times of circulation.