Abstract: In order to explore the mechanism of the resistance to gray mould induced by siderophore-producing bacterium ZJH-10, the physiological and biochemical methods were employed to study the changes in activities of superoxide dismutase(SOD), peroxidase(POD), catase(CAT), polyphenol oxidase(PPO) and phenylalanine ammonia-lyase(PAL) in cucumber roots and leaves pretreated with siderophore-producing bacterium ZJH-10 and infected by Botrytis Cinerea. The results showed that the activities of SOD, POD, CAT, PPO and PAL in the roots treated by ZJH10 increased higher than those of other treatments to some extent and reached their maximum on 5th, 3rd, 5th,3rd and 3rd in roots, respectively, the activities of these protective enzymes in leaves were accorded with those of enzymes in roots. The experimental results suggested that the increased activities of SOD、POD、CAT、PPO、and PAL induced by ZJH-10 against Botrytis Cinerea are most likely to be associated with the development of ISR in cucumber.