Abstract: Recently,some research reports showed varied endophytic bacteria in the root nodules of some legumes,which attracts great interest in research field of rhizobia. Here,we reviewed the discovery,identification of some endophytic bacteria ( Agrobacterium,non-symbiotic rhizobia,and other bacteria) in root nodules and their influence on symbiosis or plant growth,to understand the microecosystem of root nodule and to extend the field of rhizobia research.