Different conditions of Bdellovibrio bacteriovorus immobilization were investigated in this study,and the optimal conditions of Bdellovibrio bacteriovorus immobilization were confirmed by adopting sodium alginate as embedding medium,survived bacterium number as indices.Single-factor and orthogonal experiments were employed to evaluate the influences of sodium alginate concentration,calcium chloride concentration,the ratio of Bdellovibrio bacteriovorus solution to sodium alginate colloidal solution (V /V), corn oil concentration,encapsulating temperature,stirring time,stirring rate and cross-linking time on the immobilization of Bdellovibrio bacteriovorus.The results showed that sodium alginate concentration and corn oil concentration had significant influence on survival bacterium number,while calcium chloride concentration and the ratio of Bdellovibrio bacteriovorus solution to sodium alginate colloidal solution(V /V) were not in the orthogonal test for optimum carrier formula of immobilization.Furthermore,encapsulating temperature and stirring rate had significant influence on survival bacterium number while stirring time and crosslinking time were not in the orthogonal test for optimum parameters of immobilization.The optimal immobilization conditions were as follows: sodium alginate concentration of 1.5%, calcium chloride concentration of 6.5%, the ratio of Bdellovibrio bacteriovorus solution to sodium alginate colloidal solution(V /V) of 50%, corn oil concentration of 4.5%, encapsulating temperature at 47.5 ℃, stirring time for 40 min,stirring rate for 450 r /min and crosslinking time for 36 h.Under the above conditions,the logarithm of survival bacterium number of granules was up to 7.51.Therefore,the results demonstrated that the method with the properties of economy,security and good preservation has a promising future in aquaculture.