This paper reviews the legume - rhizobium of symbiotic nitrogen fixation and nitrogen fixation from rhizobia,joint symbiotic nitrogen fixation and nitrogen fixation of photosynthetic bacteria,Azolla,and the nitrogen-fixing cyanobacteria Several methods of Biological Nitrogen Fixation Research and the impact legume-rhizobia symbiotic nature of the physical and chemical factors and genetic characteristics of Rhizobium so brief.