Abstract: A total of 52 bacterium strains were isolated from healthy sea horse （Hippocampus erectus）. The hemolysis test was carried out to show that all the bacteria did not product hemolysin， so they were not pathogenic. The ability of producing protease was tested by the method of disk diffusion on the extracellular proteinase selective medium， and 2 strains secreting extracellular protease had been screened out. Safety experiments showed that 2 strains of experimental bacteria were not toxic to sea horse. The growth parameters experiment showed that the daily growth rate of body length and body weight from experimental groups were higher than the control group that fed no probiotics. Its proved that the screening strains have certain growth promoting effect， were expected to be used on aquaculture microbial preparation. Then the 16S rRNA gene sequences of 2 strains were determined. The homology of related strain sequences was analyzed for the phylogenetic tree. Combined with the biochemical phenotype and physiological characteristics， Hm7 and Hm28 were identified as Bacillus horikoshii and Pseudoalteromonas carrageenovora．