Abstract: In order to investigate the effects of different atmospheres (CO₂, N₂ and air condition) on qualities of oyster during frozen storage, modified atmosphere packaging was used in oyster storage at (-20±1℃) and then the quality indexes were measured. Results showed that: packaging atmosphere was a main factor of impacting on protein quality of oyster during frozen storage. The denaturation and decomposition of protein, the changes of pH values, the generation and breaking-up of free amino nitrogen and the increase of Total Volatile Basic Nitrogen(TVBN) value were inhibited effectively without oxygen during storage and the storage time was prolonged. Modified atmosphere packaging with N₂ was more effective than that with CO₂.