Aeromanas hydrophila B11 was investigated by the method of modified microtiter-plate test. The results showed thatB11 developed stable and evident biofilm on the surface of the polystyrene microtiter plate, and the OD₅₉₀ value of biofilm reached the secondary peak in 6 h and the highest peak in 22 h and then reduced with incubation time. The OD₅₉₀ value of the biofilm decreased with densities of initial bacterial suspension. The OD₅₉₀ value of biofilm recorded at 25 was significantly higher than those recorded at other temperatures) B11 developed evident biofilm under initial pH 510, while no evident biofilm was found under initial pH 34. When 1mmol/L magnesium ion was added, in the biofilm formation of <0.05), while calcium ion significantly promoted the formation of biofilm). Compared with the control group, only biofilm developed on the surface of the microtiter plate coated by the extract of eel’ muscle exhibited remarkably higher value of OD₅₉₀)microtiter plate coated by other extracts of tissues showed no remarkably difference) B11 strain can form biofilm on the surface of polystyrene microtiter plate; the bacterial biofilm formation can be affected by different environmental factors such as temperature, bacterial concentration, pH, Mg²⁺ and Ca²⁺concentrations and so on; muscle extract of eel can promote the biofilm formation.