The invention discloses an A-site ion-doped sodium bismuth titanate based lead-free piezoelectric ceramic and a preparation method thereof. The sodium bismuth titanate based lead-free piezoelectric ceramic has the following chemical formula: 0.852{Bi<0.5>[Na<1-x>Li<x>]<0.5>}TiO<3>-0.110(Bi<0.5>K<0.5>)TiO<3>-0.038BaTiO<3>, and the chemical formula is denoted as BNKBT-xLi, wherein 0.12<=x<=0.13. Thepreparation method comprises the following steps: respectively preparing sodium carbonate, potassium carbonate, bismuth trioxide, titanium dioxide, lithium carbonate and barium carbonate according tothe chemical formula, performing ball milling, performing drying, performing pre-synthesis on the mixed raw materials at 800-900 DEG C, performing granulation, performing molding, performing debinding, and performing sintering at 1100-1140 DEG C to obtain the high-performance A-site ion-doped modified sodium bismuth titanate based lead-free piezoelectric ceramic. The method provided by the invention not only optimizes sintering temperature, reduces volatilization of an alkali metal, but also improves strain performance, wherein the maximum strain S is 0.42%, the inverse piezoelectric coefficient d33* is 760 pm/V, and the saturation polarization intensity Ps is 34-38 [mu]C/cm<2>.