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 the sensory score decreased during storage, and got close to the sensory rejection point at 30^th day. APC decreased slightly during the first 15 days, then increased afterwards, and the value was 4.1 lg cfu·g^-1 at 60^th day. All the strains isolated from raw oysters were identified to belong to 14 genera (families), among which Pseudomonas spp. (22%) and Vibrionaceae (20%) were dominant. During -3 ℃ storage, there were different changes in the proportion of each genus, among which Pseudomonas was dominant and its proportion increased from 22% to 54% at the end of storage.