Tagged by the resistance to Rif.(300 μg/mL) and inoculated by watering root, under the sterilized soil condition, the rhizosphere bacteria AR03 strain was proved that it could colonized in root and rhizosphere soils of tobacco by artificial induction. AR03 strain could maintain considerable quantity for a while. The colonized dynamics of AR03 strain increased first, then decreased. Besides these, the colonization was greater on root than in rhizosphere. On the basis of observation of colony and cell morphology, biochemical test and the 16s rDNA sequence analysis, Strain AR03 was Bacillus pumilus.