Abstract: In order to extend the shelf life of the North Pacific squid and keep it fresh.In this study, tea polyphenols, chitosan, and their composite solutions were used as preservatives, according to determine the freshness index (sensory evaluation, total colony count, pH, TVB-N and K values) to explore the change of quality during storage period of the North Pacific squid, and determine the content changes of formaldehyde in squid. The results showed that:With the increase of refrigerated time, the sensory scores of all groups showed a downward trend, and the value of the composite group was the highest; the total number of colonies and the value of K in each group gradually increased with the extension of refrigerated time, while the total number of colonies and the value of K in the composite group was the lowest; with the increase of storage time, the pH values of the tea polyphenols group, the composite group and the blank group first decreased and then increased, while the chitosan group showed a decreasing trend; the TVB-N values of the tea polyphenols group, the blank group, and the chitosan group increased significantly after storage for 4 d, respectively.The values of TVB-N in the blank group and the composite group on the 7th day were 60.99 and 11.42 mg N/100 g; with the increase of refrigerating time, the content of formaldehyde in the preservatives group first decreased and then increased, while the blank group showed a rising trend. The content of formaldehyde in the preservatives group was lower than that in the blank group and the compound group was lowest.The blank group and composite group were exceeded on the 5th and 7th d, meanwhile the composite preservative could prolong the preservation period of the squid according to comprehensive evaluation.