Abstract: In order to reduce nutrient loss and the formation of formaldehyde in the fried squid, 2 g/L of chitosan solutions (high molecular weight chitosan and carboxymethyl chitosan) were used to treat fresh Dosidicus gigas before baking at high temperature. The results showed that the formaldehyde content in the control group (pure water immersion), chitosan group and carboxymethyl chitosan group was 45.56, 4.79, and 8.30 mg/kg, respectively. There was highly significant difference between the chitosan group and the control group. In addition, aspartic acid, serine, proline, cystine, lysine, twelve acid, pentadecylic acid, seventeen acid, octadecenic acid (n=9) and octadecenic acid (n=6), octadecadienoic acid (n=6), eicosapentaenoic acid (n=9), eicosadienoic acid, eicosatetraenoic acid, eicosapentaenoic acid(EPA), docosapentenoic acid (n=3) and elements Mg, P, Mn and vitamin C content were higher than the control group, and the other nutrients also have better keep. Squid aspartate, serine, leucine, methionine, lysine, histidine, mecilenic acid, pentadecoic aci, hexadecenoic acid (n=7), seventeen acid and eicosenoic acid (n=9), eicosadienoic acid, eicosatetraenoic acid, eicosapentaenoic acid (EPA) K, Mg, P and elements, Zn, Mn, Se and vitamin B in carboxymethyl chitosan group were higher than the control group, the other nutrients also have better keep. There was significant difference in nutrients between carboxymethyl chitosan group and control group. EPA, DHA, and amino acids can be maintained well in treated groups, especially better in high molecular chitosan group. It can be concluded that the two kinds of chitosan, especially the high molecular weight chitosan can significantly inhibit the formation of formaldehyde and can maintain the better quality and nutrients keep in squids during the baking process.