Abstract: Deuterated water(D₂O), as an important chemical raw material, plays an irreplaceable role in the nuclear energy industry, particularly as a moderator and coolant in nuclear reactors. Water distillation is regarded as an effective method for dehydrogenation and deuterium enrichment, and its separation efficiency directly determines the purity of D₂O. However, due to the extremely small vapor pressure difference between D₂O and H₂O, highly efficient gas-liquid contact and mass transfer within the column are required in the D₂O-H₂O distillation process. Among the various factors, packing performance is identified as a key determinant of mass transfer efficiency. The wettability of the packing surface is known to significantly influence liquid film spreading, interfacial renewal, and the effective mass transfer area. Although extensive studies on packing materials have been reported, the mechanism by which packing wettability regulates mass transfer behavior in D₂O-H₂O isotope distillation remains insufficiently understand, particularly when dynamic interfacial phenomena are taken into account. In this study, a combined experimental and theoretical modeling approach is employed to systematically investigate the effect of packing surface wettability on the mass transfer performance of D₂O-H₂O distillation. Copper-based packings with different hydrophilicities are prepared via surface modification, and their surface morphology, crystal structure, elemental distribution, wettability, and long-term stability are characterized. Under total reflux conditions, the height equivalent to a theoretical plate(HETP) is adopted as the primary evaluation metric to assess mass transfer performance. Furthermore, the influence of the packing surface contact angle and gas velocity on HETP and pressure drop is analyzed. An HETP prediction model associated with mass transfer is established based on the surface renewal theory. By introducing a wettability parameter, the model couples packing surface properties with liquid film renewal behavior, thereby elucidating the influence of dynamic gas-liquid interfacial renewal on the mass transfer process. The results show that enhancing the hydrophilicity of the packing improves interfacial renewal and significantly reduces the HETP value. A moderate increase in gas velocity further enhances mass transfer efficiency without a noticeable rise in pressure drop, indicating a synergistic effect between wettability and operating conditions. The proposed HETP prediction model shows excellent agreement with experimental data, with a coefficient of correlation(R²) of 0.996 and relative errors controlled within 20%, indicating good predictive accuracy and applicability. These findings demonstrate that, compared with the conventional two-film theory, the surface renewal model provides a more realistic description of the dynamic mass transfer behavior in D₂O-H₂O distillation. This study provides a theoretical basis for packing design and process optimization in the D₂O-H₂O distillation system and offers valuable guidance for isotope enrichment and the design of high-efficiency distillation columns.