This experiment was systematically performed by sampling and investigation, collecting data and organization to legume plant Sophora alopecuroides grown in part regions in different eco-regions (Gansu, Ningxia and Shaanxi) of northwestern China, which provided a base for further study of legume plant associated with rhizobia in northwestern regions. Result by comparison showed that shape of most rhizobia grown in field is claviform, spherical, minority coralliform, while most of rhizobia during nodule assay...