As one of the rhizospheric microorganisms PGPR(Plant Growth Promoting Rhizobacteria) and AMF(Arbuscular Mycorrhizal Fungi) play an important role in promoting plant growth. It is of significance to further study and elucidate the interactions between them to utilize and regulate the interactions among rhizospheric microorganisms, and promote and protecte plant growth. Many research results show that on one hand, there exists synergism between PGPR and AMF. AMF can transfer PGPR or act as a media in the process of spread of PGPR along roots, where PGPR create many beneficial conditions for the infection of AMF. Both of them can indirectly enhance the other side's colonization or infection ability through their own promoting role on plant growth. On the other hand, they compete with each other for nutrients and niches, and probably produce some secondary metabolites which cause detrimental effects on the other. However, whether these interactions are synergistic or competitive depends upon the AM fungal or PGPR species involved. So far, the research work is extensive, even in molecular level in some aspects, but not systematic and deep. It is believed however, with the development of techniques in molecular biology and the increasing application of advanced testing methods, the new breakthroughs will be gained in the study and understanding on the interactions.