Using immobilized mucosal model in vitro, combined with the isotope tracing method, the adhesion characteristics of Enterococci,Citrobacter isolated from carp intestines and Bacillus isolated from water to the carp foregut mucus were investigated. Results showed that after the modification with proteolytic enzymes or sodium metaperiodate, the relative adhesion percentages of all five bacteria were declined extremely significantly after they were treated with sodium metaperiodate(P<0.01), but it was affected less by the proteolytic enzymes treatment（P>0.05）, indicating that main lectins existing on the cell surface of the five bacteria are glycoprotein compounds. After the modification with proteolytic enzymes or sodium metaperiodate of mucus, the relative adhesion percentages of part of five bacteria were declined significantly after the mucus was treated with proteolytic enzymes(P<0.05), but it was affected significantly by the sodium metaperiodate treatment(P<0.05), indicating that the special receptors of the microorganisms are protein compounds. According to the interactions such as exclusion, competition, and displacement, the five probiotic bacteria can reduce the relative adhesion percentages of part pathogens significantly. The inhibition of displacement to the pathogens was best, but the disparity was led by the different strain.