Abstract: Effects of antibiotics including kanamycin (Kan) G418, carbenicillin (Cab) and cefotaxime (Cef), on the growth and differentiation or rooting of various explants of Populus alba were studied.The optimum concentrations of bacterium inhibition and genetically modified organism selection of Populus alba were determined in Agrobacterium-mediated transformation.The optimum concentrations of Kan, G418 Cab and Cef are 15mg/L, 10mg/L, 200-600mg/L and 200-400mg/L at the stage of screening culture where leaves were used as explants and are 20-25mg/L, 15-20mg/L, 200-800mg/L and 200-600mg/L at the stage of subculture or rooting of resistant buds.The inhibitive effects of Cef and Cab upon Agrobacterium tumefaciens vary with the strains of Agrobacterium.Cab is a better choice to inhibit Agrobacterium LBA4404 and Cef is more propitious to inhibit Agrobacterium C58.