The mucus layer is the most outer defence barrier of fish. The bacterial attachment to mucus layer is a critical step in the host colonization and subsequent occurrence of infection. Adhesion of Vibrio alginolyticus to the intestinal mucus of Pseudosciaene crocea has been investigated in order to understand the characteristics and mechanisms involved in the adherence of bacteria onto fish mucus so that preventive measures can be devised to reduce infection. In vitro adhesion assay was carried out by bacterial counting. The adhesive bacteria were stained with SYBR Green Ⅰ , observed under fluorescent microscope, counted on computer display after taking pictures. The results showed that the adhesive quantity of V. alginolyticus increases with bacterial concentrations and reached equilibrium after being incubated 1 - 1.5 h;the higher adhesive quantity was achieved at 15 - 30 ℃ and acid condition; adhesion of V. alginolyticus to the mucus of foregut was not obvious variety with salinity（5 - 35） ,but adhesive quantity to the hindgut mucus enhances while salinity increases; V. alginolyticus could not adhere to intestinal mucus without salinity; adhesive quantity reduced remarkably after heat treatment of the germ（56 ℃ 5 min, 60 ℃ 1 h）, which indicated that heat sensitive structure of V. alginolyticus might play an important role in adhesion. The conclusions of this paper showed V. alginolyticus could adhere to intestinal mucus of P. crocea facilely in seawater; this adhesion was remarkably affected by environmental factors, such as temperature, pH and salinity; V. alginolyticus adhered to the intestinal mucus of P. crocea by specific adhesion, some heat-sensitive structures on V. alginolyticus surface played a crucial role in adherence of the bacteria to gill mucus. The results indicated that the bacterial adhesion of V. alginolyticus to intestinal mucus of P. crocea was govemable. The results obtained are useful for the epidemic control in fish culture.