Endophytic bacteria B20-006,an antagonistic microbe,was applied to coat maize seeds and resulted in 67.9% control effect on maize sheath blight caused by Rhizoctonia solani.Moreover,B20-006 was ensured the ability to penetrate roots,and in turn move along vascular elements of maize plants.For further study of biocontrol mechanism of the antagonistic agent,the changes of major defensive enzymes(PAL,POD,SOD and EST) in specific activity were assayed in plants due to interaction between B20-006 and host maize.