Abstract: Objective To study the influence of different concentration of Al₂O₃ nanoparticle (20nm in average) on RP4-mediated conjugation.Methods Mating was conducted at 25℃ in saline beriveen E coliB 101 (RP4) and Salmonella aberdeen Kauffmann 50312(str)without stirring and the donor per recipient ratio was 1:3 constantly.Results Aftet mating for 8 h,5 mm of/L Al₂O₃ nanoparticle could increase the conjugative transfer frequency by approxin ately 100 to 400 folds as the donor and recipient varied at the range of 10⁶-10⁸ cfu/mL,which was the most significant among all concentration of Al₂O₃ nanoparticle adopted,but the effect of other concentration of Al₂O₃nanoparticle varied as the starting concentration of donor and recipient changed 50 mm of/L Al₂O₃ nanoparticle could enhance RP4 conjugative transfer by 40-fold only when donor and recipientw ere both 10⁸ cfu/mL,some what less than 5 mmol/L,group.When donor and recipient varied beriveen 10⁶-10⁷ cfu/mL,0.5mm of/L Al₂O₃ nanoparticle could activate RP4 conjugative transfer in turn significantly.When donor and recipientwere both 10⁵ cfu/mL,no tmnsconjugant appeared in all groups Prolonging mating tin a to 90 h,0.5 mm of/L Al₂O₃ nanoparticle could increase transconjutant number,and shorten the tine of tmnsconjugant showing up.Conclusion The result suggests that Al₂O₃ nanoparticle can stir ulate donor function and thus result in a significant increase in conjugative plasmid dissemination in aquatic environments.