This study investigated the leaf anatomical structure and ion metabolism characteristics of seedlings of three Ping'ou hybrid hazelnut varieties under salt stress, to reveal the salt stress response and adaptation mechanism, and the salt tolerance differences of different varieties. Three Ping'ou hybrid hazelnut varieties (Dawei, Liaozhen 7, Yuzhui) were selected as testing materials. The two-year-old seedlings were treated with control, mild, moderate and severe salt stress (0, 50, 100, and 200 mmol/L NaCl concentrations, respectively) in a pot experiment. Subsequently, the leaf microanatomic structure parameters and the variation of ions (Na⁺, K⁺, Cl^-, Ca²⁺) content were analyzed. The absorption, transportation and distribution of these ions in roots, stems and leaves were investigated. With the increase of salt stress, the leaf thickness, upper epidermis thickness, lower epidermis thickness, palisade tissue and spongy tissue thickness of different Ping'ou hybrid hazelnut varieties increased first and then decreased, and these parameters under mild and moderate stress were significantly higher than those of the control group. The moderate salt stress significantly improved the leaf structure tightness of all varieties. Compared with the control, salt stress significantly increased the Na⁺ and Cl^- content in roots, stems and leaves of Ping'ou hybrid hazelnut. Under salt stress, the absolute contents of Na⁺ and Cl^- in leaves were significantly higher than those in stems and roots, however, the increase of the two was the largest in roots and the smallest in leaves, which indicated that the roots of Ping'ou hybrid hazelnut could absorb and intercept a certain amount of Na⁺ and Cl^- and then transport them to stems and leaves. Compared with the control, the absorption of K⁺ and Ca²⁺ by roots and stems remained stable or decreased under mild and moderate salt stress, while K⁺ content in roots, stems and leaves and Ca²⁺ content in leaves and stems decreased significantly under severe salt stress. Salt stress significantly reduced the K⁺/Na⁺ and Ca²⁺/Na⁺ ratios in roots, stems and leaves. With the increase of salt stress, the S_K⁺,Na⁺ and S_{Ca²⁺,Na⁺} from root to leaf and from stem to leaf of different Ping'ou hybrid hazelnut varieties increased first and then decreased. The effects of salt stress on S_K⁺,Na⁺ from root to stem of Liaozhen 7 and Yuzhui were not significant. Under salt stress, the leaves of Ping'ou hybrid hazelnut could adapt to the saline habitat through a series of morphological structure adjustment. When accumulating salt ions, Ping'ou hybrid hazelnut could enhance the selective absorption and transportation capacity of K⁺ and Ca²⁺ to maintain the ion balance and high K⁺/Na⁺ and Ca²⁺/Na⁺ ratios, so as to maintain the normal physiological and metabolic activities under salt stress. The Liaozhen 7 showed stronger morphological and physiological adaptability to salt stress, and its salt tolerance was stronger than that of Dawei and Yuzhui.