The expressed outer membrane protein (Omp,about 52 ku) of Edwardsiella tarda was purified after the recombinant expression vector was constructed,transferred into E.coli BL21 and induced.A total of 100 healthy Japanese eels (Anguilla japonica) was divided into 2 groups and intraperitoneally injected (i.p) with bovine serum albumin (BSA,0.5 mg/mL) and the outer membrane protein (Omp,0.5 mg/mL),respectively.On 7,14 and 28 d post-vaccination,the blood,skin mucus,liver and kidney of eels were collected to evaluate the lysozyme and complement activities,stimulation index and specific antibody titers.The complement activities in the Omp group were extremely significantly（P＜0.01） higher than that of the BSA group on 7 d.The specific antibody titers in the Omp group were significantly (P＜0.05 or P＜0.01） higher than that of the BSA group on 14 d and 28 d.The lysozyme activities and stimulation indexes showed no significant difference (P＞0.05) between two groups.The relative percent survival (RPS) of Omp were 71.4%,50.0% and 12.5% respectively after challenged by E. tarda,A. hydrophila or V. vulnificus.These results suggested that the recombinant expressed Omp could significantly improve the immune function and resistance of A. japonica against E. tarda.It also had significant cross protection against A. hydrophila,but had weak cross protection against V. vulnificus.