Using low-field NMR, nuclear magnetic imaging and one dimensional frequency coding techniques to study changes in water content and migration of pork longissimus dorsi at -18 ℃ after frozen storage for 0d and 1, 3, 6, 9, 12 and 15 months. Regularity, the changes in TVB-N, TBARS, drop loss, and protein solubility during the storage of pork were determined, and a comprehensive analysis of the correlation between changes in water and quality indicators was performed. The results showed that there were 3 components of water in the longissimus dorsi muscle: T₂₀, T₂₁, and T₂₂. As the time of freezing increased, The T₂₁ component decreased and the T₂₂ component increased. MRI showed that with the extension of time, the water distribution of the sample was uniform from the initial distribution to the strong signal at the edge of the sample, and the signal in the middle was low. With the continued deepening of frozen time, it gradually returned to a uniform state. After 15 months, the final moisture distribution was even. And using one dimensional frequency coding, it was found that the signal quantity (magnitude) of moisture in meat gradually decreased with the prolonged storage time. The correlation analysis showed that: T₂₁ was significantly associated with frozen storage time, TVB-N, TBARS, drop loss rate, and protein solubility (P＜0.05). T₂₂ was significantly associated with frozen storage time and TVB-N (P＜0.01). T₂₂ and TBARS, drop loss rate, protein solubility was significantly related (P＜0.05), T₂₁, T₂₂ and meat quality indicators showed a good correlation.