Abstract: The changes in the sensory property, aerobic plate count (APC) and microbial flora of Pacific oyster (Crassostrea gigas) during storage at -3 ℃ were analyzed. The results showed that sensory score decreased during storage, and got close to sensory rejection point at 30th day. APC decreased slightly during the first 15 days, then increased afterwards, and the value was 4.1 lg cfu.g-1 at 60th day. All the strains isolated from raw oysters were identified to belong to 14 genus (family), among which Pseudomonas spp. (22%) and Vibrionaceae (20%) were dominant. During -3℃ storage, there were different changes in the proportion of each genera, among which Pseudomonas was dominant and its proportion increased from 22% to 54% at the end of storage.