The Zhanjiang cultured Penaeus vannammei were preserved at(4±1)℃ and its bacterial composition were studied qualitatively and quantitatively through the bacterial morphology and physiological-biochemical experiment at different stages during refrigeration.Furthermore,the dominant spoilage organisms were identified preliminarily.The results indicated that the total number of bacteria was 2.8×104 CFU/g at the initial storage,including 10 genera of bacteria with 6 Gram-negative bacteria which taking up 80% of the total number of bacteria.Among them,the bacteria with highest number were Flavobacterium spp.and Aeromonas spp.,accounting for 33.3% and 13.3% respectively.After refrigerated for 2 days,the total number of bacteria was 5.1×104 CFU/g,Flavobacterium spp.(30%) and Acinetobacter spp.(16.7%) were in the ascendant and the amount of G-grew to 86.7%.As time going on,the types of bacteria gradually reduced and the total bacterial count was 3.0 × 106 CFU/g at the end of shelf life,but only 8 genera of bacteria were separated,of which the amount of G-was 93.4% and the content of Aeromonas spp.and Pseudomonas spp.both increased to 16.7% while that of Flavobacterium spp.reduced to 26.7%.The other types of G-were grown in varying degrees.On the 6th days,the total number of bacteria was up to 2.4×107 CFU/g and the Penaeus vannammei completely spoilaged.4 dominant spoilage organisms isolated from the musle of prawn were all G-,which comprised Flavobacterium spp.,Shewanella spp.,Pseudomonas spp.and Aeromonas spp.,with the proportion of 28.74%,26.44%,21.84%,and 16.09%,respectively.