Abstract: To improve the rooting ability of Populus tomentosa,the rolB gene was transformed into the plant and 7 transgenic clones were obtained.The in vitro rooting results showed that the rooting rate of transgenic clones ranged from 80% to 100% without auxin,while only 13%-20% for the control plants.Transgenic plants showed a high sensitivity to the auxin.When the concentration of IBA reached 1.0mg/L,the rooting of the transgenic clones was restrained.Growth analysis showed that the stem length of one transgenic clone was reduced and the node number of two clones was increased and the internode length of three clones was obviously reduced compared with the control plants.The hardwood cutting experiment further confirmed that the increased rooting ability of the transgenic clones ranged from 74.4% to 92.3%,and the root number was also greatly increased.