Oxidation Sodium alginate is a naturally derived cross-linking agent. It has the advantages of high biocompatibility, no precipitation, and low toxicity that small-molecule aldehydes do not possess. Herein, we employed sodium periodate for the oxidation of sodium alginate (SA) to produce oxidized sodium alginate (OSA) aldehyde-based crosslinker, which was used to crosslink calcium alginate (CA)/Antarctic krill protein (AKP) composite fibers to obtain OSA-co-CA/AKP composite fibers with multiple crosslinking networks. FT-IR was used to analyze the multiple cross-linked network construction and the hydrogen bonding mechanisms. The composite fibers' crystallinity, morphological structure, and thermal and mechanical properties were analyzed by XRD, SEM, DSC, TGA, and a single fiber strength meter, respectively. The results showed that the composite fibers possessed a multi-network structure of covalent bonding-ionic complexation-hydrogen bonding. And the inclusion of OSA enhanced the composite fibers' thermal stability, crystallinity, and mechanical properties. When the OSA was 1.64 wt%, the fracture strength and salt resistance increased by 16.58 % and 44.2 %, respectively. Cell Counting Kit-8 cytotoxicity test also verified its good biocompatibility and confirmed its potential as a biomedical material.