The passive NO_x adsorbent, Pd-SSZ-13 with a Pd loading of 1.64wt.%, was prepared by the ion-exchange method. Then, the Pd-SSZ-13 was subjected to thermal and hydrothermal aging treatments separately for 10h under mild conditions: at a temperature of 700℃ and in an atmosphere consisting of 10%O₂, 2%H₂O (for hydrothermal treatment only), and N₂ as the balance. The effects of these treatments on the NO_x adsorption/desorption performance of Pd-SSZ-13 were investigated. The physicochemical properties of adsorbents and the NO adsorption process were characterized using N₂ adsorption-desorption, XRF, ICP-OES, XRD, SSNMR, XPS, TEM, NH₃-TPD and in situ Drifts techniques. The results showed that when the feed gas contained 2%H₂O, the SSZ-13 support was unable to adsorb NO_x, whereas Pd-SSZ-13 exhibited NO_x adsorption during both the adsorption stage and the temperature-programmed stage (100~230℃), demonstrating an adsorption capacity of 81.3μmol/g. The NO_x desorption temperature range (230~493℃) fell within the active temperature window of SCR catalysts, and complete NO_x desorption was achieved. After undergoing thermal and hydrothermal aging treatments, the NO_x adsorption capacity of Pd-SSZ-13 in the presence of H₂O further increased to 113.4 and 126.2μmol/g, respectively, and the thermally aged sample showed better cyclic stability. Although thermal and hydrothermal aging treatments induced partial dealumination of the SSZ-13 framework, they neither altered the micropore characteristics of SSZ-13 nor caused structural collapse or framework destruction. Instead, the aging processes promoted the migration of Pd species from external surfaces to interior pores, enhanced the dispersion of Pd, and increased the amount of Pd²⁺(Z-[Pd²⁺(OH)]⁺ and Z₂-Pd²⁺) sites, thereby improving the NO_x adsorption-storage capability of Pd-SSZ-13. Compared with the hydrothermally-aged Pd-SSZ-13, the thermally-aged sample showed less framework dealumination, a higher specific surface area and a larger micropore volume, and better dispersion of Pd species, all of which likely contributed to its superior cyclic stability. With H₂O in the feed gas, NO was mainly adsorbed and stored at the Pd²⁺ sites in the forms of Pd⁺-NO, Pd²⁺-NO and hydrated Pd²⁺-NO species, with the competitive adsorption of H₂O attenuated at elevated temperatures. During the thermal and hydrothermal aging of Pd-SSZ-13, the abundant Brønsted acid sites likely played an important role in facilitating the migration of Pd species and the formation of Pd²⁺ sites.