Herein, Ag_1-3xSm_xNbO₃ (0 ≤ x ≤ 0.025) antiferroelectric ceramics were successfully synthesized by solid state methods. The effect of Sm³⁺ doping on the structure, property and energy storage performance were studied. With the increasing Sm³⁺ concentrations, the average grain size decreased. Meanwhile, the stability of high temperature M phases (i.e., the structure between T_f and T₃) was expanded, which led to low loss for energy storage. Both of structure analysis and ferroelectric tests revealed the existence of weakly polar/AFE-like phase below T_f. The Sm³⁺ doping tended to suppress the ferroelectric behavior and expand the stability of antiferroelectricity. Consequently, a significantly enhanced energy storage performance (W_rec = 3.8 J/cm³, η = 73 %) could be achieved in Ag_0.97Sm_0.01NbO₃ ceramic, which was almost 1.5 times larger than that in non-doped AgNbO₃ (W_rec = 2.4 J/cm³, η = 45 %) under the similar applied field of 1705 kV/cm. In particular, the performance of the ceramic showed great temperature stability with variation of 5 % from 25 ℃ to 125 ℃. These results indicated that the Ag_0.97Sm_0.01NbO₃ ceramic could be an ideal lead-free candidate used in the energy storage field.