Potassium sodium niobate (K_0.5Na_0.5NbO₃, KNN) based ceramics can be widely used for pulsed power systems due to their fast charge-discharge rate, high transparency, wide range of working temperature, and long cycle life. Improving the electrical and optical property of KNN-based ceramics through modification is a research hotspot in this field. 0.825(K_0.5Na_0.5)NbO₃-0.175Sr_1-3x/2La_x(Sc_0.5Nb_0.5)O₃ (x=0, 0.1, 0.2, 0.3) (0.825KNN- 0.175SLSN) ceramics were synthesized by solid state method. The effect of La₂O₃ doping on the phase structure, microstructure, optical property, dielectric property, ferroelectric property and energy storage property of the ceramic was studied. The results indicated that the structure of 0.825KNN-0.175SLSN ceramics is pseudo-cubic phase with high symmetry. With increment of La₂O₃ content, the average grain size of 0.825KNN-0.175SLSN ceramics decreased, and the phase transition temperature (T_m) and saturation polarization intensity (P_max) increased and then decreased. 0.825KNN-0.175SLSN ceramics exhibit excellent transparency at x=0.3, the transmittance in the visible wavelength (780 nm) and near-infrared wavelength (1200 nm) ranges reaches 65.2% and 71.5%, respectively. The dielectric breakdown strength of 310 kV/cm and a recoverable energy density of 1.85 J/cm ³ are achieved at x=0.3.