Effect of the different concentrations of formaldehyde（FA） on the gel properties of myofibrillar proteins（MP） in Peru squid（Dosidicus gigas） were investigated by in vitro simulation. The results showed that the whiteness， hardness， chewiness， breaking force and cooking loss of MP gels increased significantly with the increase of FA concentration， whereas water-holding capacity， the sulfhydryl groups and surface hydrophobicity decreased gradually， which indicated that the retention water of proteins gel became worse. The chemical interactions （hydrogen bonds， disulfide bonds， ionic bonds， hydrophobic interactions） and peaks area proportion of transverse relaxation time T2 of treatment groups changed obviously， especially for the peaks area proportion of T23 and T24， which indicated that protein conformation was changed and water flowing of protein gels showed increasing with the presence of FA. The FE-SEM observed that microstructure of gel sample of the treatment groups were more rough， uneven， large gap and fragile， which showed that the network structure of the protein gels was damaged when the presence of FA and its became loose and easy to break.