Sodium potassium niob ate-based piezoelectric ceramics have attracted much attention due to their excellent electrical properties, which has been considered to be one of the most promising lead-free piezoelectric ceramics to replace lead-based ceramics. In this work, the influence of doping Bi_0.44Fe_0.06Ag_0.03Na_0.47ZrO₃ on the crystal structure, micro structure and electrical properties of K_0.48Na_0.52Nb_0.96Sb_0.04O₃ lead-free piezoelectric ceramics were investigated systematically. All the compositions exhibit a pure perovskite structure with rhombohedral and tetragonal coexistence. The grain size of ceramics first increases and then decreases with the increase of Bi_0.44Fe_0.06Ag_0.03Na_0.47ZrO₃. Finally, the optimal electrical performances of d₃₃ = 322pC/N, k_p = 41.34%, ε_r = 2441, tanδ = 0.036, d₃₃^* = 400pm/V, and P_r = 15.94μC/cm² were obtained by optimizing the crystal and microstructure.