The lead-free antiferroelectric material NaNbO3 (NN) is highly regarded for its exceptional breakdown electric field strength (Eb) and substantial recoverable energy storage density (Wrec). However, the significant energy loss of NN reduces its Wrec and η under a strong electric field, constraining its application in energy storage domains. This study explores a novel approach by integrating the relaxation ferroelectric (Bi1/2Na1/2)1/2Sr1/2TiO3 (BNST) into NN to create NN-BNST relaxation anti-ferroelectrics, aiming to enhance their energy storage capabilities. The incorporation of BNST not only effectively reduces the grain size of NN but also disrupts its long-range ordered structure, forming polar nanoregions (PNRs) that mitigate energy density loss. Both Wrec and η of NN ceramic are significantly improved with increasing the concentration of BNST. Optimal results are achieved with the 0.75NN-0.25BNST ceramics, which demonstrate a high energy storage density (Wrec = 3.83 J/cm3) and conversion efficiency (η = 76 %) while achieving an Eb of 236 kV/cm. The analysis of Eb enhancement in NN-BNST ceramics is conducted through considerations of grain size, band-gap width, and activation energy, offering a robust framework for developing new NN-based antiferroelectrics for energy storage applications.