Salt stress reduces plant growth and is now becoming one of the most important factors restricting agricultural productivity. Inoculation of plant growth-promoting rhizobacteria (PGPR) has been shown to confer plant tolerance against abiotic stress, but the detailed mechanisms of how this occurs remain unclear. This project intends to evaluate the changes of rhizosphere flora of maize in saline-alkaline land after the use of P8/P10/X52 group. To know whether the change of rhizosphere flora structure improve the plant tolerance against salt stress.