The total numbers of 69 root nodules which were collected dispersed over 21 genera, 45 species of legumes according to our investigation of rhizobium resources of leguminous plant in Bailong river basin, Gansu province, 63 strains of root nodule bacteria from 69 samples were isolated. Experiments on 44 stains among 31 were inoculated back to 13 species hosts. The shapes of nodules of these plants were circular, ellipse or cudgel with pick in color. The results of acetylene reduction detection showed that 88.5% were effective for nitrogen fixation. Activities of nitrogen fixation in nodules varied littlely and were higher than that in other areas of Gansu province.