Endogenous nitrogenfixing bacteria is one of important plant promoting growth bacteria and occupies the plant tissue which is conductive to nutrient supply and suitable micro ecological environment and can better promote growth.The promoting plant growth mechanisms includes nitrogen fixation，phosphate solubilization，phytohormone production，ACCdeaminase production and suppression of pathogens.In this study，eight endogenous nitrogenfixing bacteria were isolated from the root of potato and were identified as Brevibacterium (3)，Bacillus (3)，and Pantoea (2).The results of functional characterizations showed that the nitrogenase activity of Brevibacterium spGWR4 was 16.206 nmol C2H4/(mg protein·h)，which was significantly higher (P＜0.01) than that of Azotobacter charoococcum. Pantoea sppGWR2 with ACCdeaminase activity and GWR3 with solubilization of inorganic phosphate had high capacities of IAAproduction with 186.07 μg/mL and 162.21 μg/mL，respectively.Brevibacterium spGWR5，with solubilization of organic phosphate and production of IAA，had the capability to antagonize the growth of Fusarium solani MLSQB and Fusarium xysporum MLSOF.Bacillus sppGWR7 and GWR8 had the nitrogenase activities and produced IAA.The pot trial showed that the fresh weights of Chinese cabbage inoculated with GWR3，GWR4，GWR5，GWR7，GWR8 were significantly higher than that with no inoculation control，respectively.The five bacteria with functional characterizations should have good application prospect.