Abstract: Abstract: In the previous optimization test, relative content of salt-soluble protein, gel strength of surimi gel, washing loss rate were used as the indices to study the influence of different salt solution washing on the hairtail surimi quality, and the optimum concentration of each single-component salt solution (0.30% NaCl, 0.06% CaCl2 or 0.50% sodium citrite) was determined. Then the above-mentioned 3 kinds of salt solution were mixed in certain proportion, and their optimal proportions (0.15% NaCl, 0.04% CaCl2 and 0.35% sodium citrite) in the compound salt solution were obtained by the orthogonal array design. In this paper, the water relaxation time (T2) and proton density of hairtail surimi gel were explored by the low-field nuclear magnetic resonance (LF-NMR). Using the moisture content, water holding property, gel strength, photographs of scanning electron microscope (SEM) of hairtail surimi gel as the indices, the effects of single-component salt solution and compound salt solution on the properties and moisture distribution of hairtail surimi gel were studied. Results of LF-NMR showed that the water in the hairtail surimi gel was bound stronger and its degree of freedom decreased after the washing treatment by 4 groups of salt solution. According to the data of texture analyzer and SEM, the surimi washed by NaCl, CaCl2 solution showed a higher gel strength, and a denser and more uniform aperture of gel network. Combining the water distribution and water holding capacity of the surimi gel, the results showed that the immobilized water in the gel of surimi washed by NaCl or CaCl2 solution was not easy to turn into the free water, and their water holding capacity were stronger than those in the gel of surimi washed by sodium citrite or compound salt solution. The reason might be the contraction and denaturation of protein induced by NaCl or CaCl2 solution, which caused the decrease of the binding ability of water in some extent, and the effect of CaCl2 solution on the contraction and denaturation of protein was more obvious. The myofibrillar protein of hairtail surimi was flaccid by the rinse with the sodium citrite solution, which led to the exposure of hydrophilic group, then the water were intercepted by the surimi gel network under the influence of hydrophilic group. This was the reason that the free water content was the least in the gel of surimi washed by CaCl2 solution. When the 3 kinds of salt solution (NaCl, CaCl2, and sodium citrite) were mixed during the washing treatment, the synergistic effect was produced. The gel of surimi treated by the compound salt solution had higher moisture content, lower free water content, better water holding capacity and gel strength, and denser network. Compared to the single component, the hairtail surimi rinsed with the compound salt solution has a better quality.