Objective To identify the natural protein arginine kinase (AK) extracted from oysters, and to understand its basic properties and homology. Methods AK was isolated and purified from oysters by ammonium sulfate salting out and anion exchange, and the relative molecular mass and secondary structure were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism (CD) spectroscopy. Its stability was also studied. The amino acid sequences of oyster AK and 11 other crustacean and mollusk allergens were compared by bioinformatics software, and their homology was analyzed. Results The natural protein with a relative molecular weight of 40 kDa was oyster AK. AK was neither heat-resistant nor acid-resistant. Oyster AK has high homology of mollusk allergen AK amino acid sequence, and homology of crustacean amino acid sequence is 55%-60%. Conclusion Natural AK is extracted from oysters, and the stability and homology are basically understood. It will lay the foundation for comprehensive research on sensitization and sensitization mechanism of oysters.