Abstract: The bacterial strain B was used to control chinese cabbage soft rot in field The results showed that the infection of pathogen on leaves was reduced by 67%, and a 59.8% controlling effect on incidence of disease was obtained It also indicated that bacterial strain B may induce the increase of peroxidase in the plants of chinese cabbage, the averaged OD of peroxidase was increased by 24.6% when comparing with the control The treated chinese cabbage resisted to Erwinia carolovora The preliminary conclusion is that strain B is a promising bacterium for biocontrol purposie.