Abstract: Wheat seeds were inoculated respectively by different combinations between associative azotobacteria and rhizobia，and then planted in the pots filled with sterilized vermiculite for 28 days．The fresh weight，dry weight，total N ，the rate of F_v /F_m of wheat seedlings and root nitrogenase activity were measured．The results show that root nitrogenase activities of the seedlings inoculated by associative azotobacteria can be detected，some come up to 386．6(±3．5)nmol／g(fresh weight)．And the dry weight，total N，the rate of F_v /F_m of most seedlings inoculated together by associative 87．0-tobacteria and rhizobia are a little higher than those inoculated by only one kind of associative azotobactefia．Especially the nitrogen-fixing ability of combination between Klebsiella oxytoca and Sinorhizobium melilot Ⅱ is more notable and has application potential on the agricultural production．