The paper aims to investigate the oxidation rule of muscle protein in mackerel during the frozen storage. Mackerel was stored at -18 ℃ for 10, 20, 40, 60, 80 and 100 d, respectively. The pH value, color, muscle texture properties of mackerel were determined. Myofibrillar protein was extracted to measure the content of hydroxyl, sulfydryl and surface hydrophobicity. With the increase of frozen time, the pH value of mackerel decreased first and then increased. In the determination of color difference, L* and a* value of mackerel decreased continuously. The hardness, elasticity, adhesiveness and mastication of the samples also decreased. The longer the storage time was, the more obvious the decrease was. The content of carbonyl and hydrophobicity of protein surface in mackerel increased with the increase of storage time, while the content of sulfhydryl decreased with the increase of storage days. The protein quality of mackerel decreased slightly in the early stage of low temperature frozen storage, but decreased greatly with the increase of time.