Tabocco PGPR strains Pseudomonas fluorescens RB-89 and RB-42 had high dgree chemotaxis towards roots exudates.The Che are 1.79 and 1.93 of P. fluorescens RB-89 and RB-42 at five hundreds times dilution of the condense of tobacco roots exudates . The two strains had higher chemotaxis towards amino acid than organic acid and the carbohydrates. The chemotaxis of P. fluorescens RB-89 and RB-42 showed great difference among amino acids, the strains had a high chemotaxis toward Tyr Pro Gly Phe but showed no chemotaxis toward His and Thr. The strains showed almost no different chemotaxis to organic acid but showed higher chemotaxis to lactic acid than ohters. The strains showed no chemotaxis toward the carbohydrates. The colonization on tabacco roots of P. fluorescens RB-89 and RB-42 were deeply influenced by soil sterilization and chemotaxic materials and the colonization density were improved greatly with soil sterilization and chemotaxic materials.