89 strains of root nodule bacteria from different species of tree legumes were isolated following the method suggested by Vincent (1970). Inoculation of locust water culture and pot experiments confirmed that strains 92-1-11, 84-21, and 92-125 not only formed nodules on locust root both large and abundance, but show great nitrogenase activity more than 1000 (amolC2H4/g(fresh nodule)·h, and go beyond the level of the nitrogen fixed by efficient soybean root nodule bacteria. They bring about a great advance in locust growth. The average fresh weight of two months plant exceed 5 grams, show a marked increase over CK-plant, more than 82%. We consider that 92-1-11, 84-21 and 92-125 are efficient strains, can accomodate as probationary strains used in forest production.