Abstract: In order to screen out the antagonistic bacteria that have a good inhibitory effect on Rosa roxburghii Tratt powdery mildew disease,from healthy Rosa roxburghii Tratt and its root soil,Sphaerotheca pannosa was used as a target strain and the antagonistic bacteria were treated with leaf disk method.the antagonistic bacteria were identified by morphological,physiological and biochemical characteristics,bacterial 16s rRNA. And by measuring the OD value antagonistic bacteria draw the growth curve. Exploring the antagonistic effect on powdery mildew spore germination and mycelium and enzyme production. The results showed that 48 strains of bacteria were isolated,which JK-6 and JK-32 had significant inhibitory activity,identified as Bacillus amyloliquefaciens and Bacillus aerius,and the control effect reached 60% and 57%. At the same time,under the action of antagonistic bacteria,the spores of pathogenic bacteria caused abnormal swelling during germination,and the surface of the mycelium became rough,swollen,entangled and fused. Enzyme production showed that both antagonistic bacteria could produce protease,cellulase and pectinase. It provided the theoretical basis for the biological control of powdery mildew of prickly pear and had further research value.