sRNAs are small non-coding RNAs in bacteria and take participate in various cell processess at post-transcriptional level. To find out the cell-density related sRNAs involved in virulence regulation in fish pathogen, Vibrio alginilyticus, RNA-seq was carried out to characterize the differentially expressed genes at low cell density and high cell density cultures of Vibrio alginolyticus. On the basis of the RNA-seq results, the bioinformatics method was utilized to screen out the cell density related sRNAs.