Abstract: In order to investigate the growth promoting effect of inoculating Klebsiella variicola DX120E, a bacterial strain with high activity of associative nitrogen fixation, on sugarcane, the strain was inoculated through roots into the pathogen free micropropagated seedlings of two sugarcane cultivars B8 and GT21. The bacterial numbers colonized in sugarcane plants, the activities of the key enzymes for nitrogen metabolism, the nitrate concentration and nutrient uptake were analyzed. The results indicated that the DX120E strain could live, propagate and colonize in the roots and aerial parts of sugarcane seedlings. The DX120E inoculation could effectively promote the plant growth and nutrient uptake, significantly improve the nitrate reductase (NR) activities, and increase the glutamine synthetase (GS) activities and nitrate concentration in certain degree in the leaves, compared with the uninoculated seedlings. It was suggested that Klebsiella variicola DX120E possesses a significant growth promoting effect on sugarcane plants which has a great application potential in developing biological nitrogen fixation fertilizer for sugarcane.