Abstract: Using the PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) technique, the bacterial community structure was analyzed of the rhizosphere soil collected from six orchards in Shanghai where root nodule caused by Agrobacterium tumefaciens happened in varying degrees. The peach trees of 3 cultivars and the pear trees of 2 cultivars were involved, and their ages were ranged from seven to nine years. The analysis results indicated that significant differences in bacterial community structures were found among different gardens. All the samples from the same orchard were divided into the same cluster group, with a similarity of 75%. Based on the results of principal component analysis (PCA), it is found that insignificant differences in the rhizosphere bacterial community structure were noted among the soil samples with different disease indices in the same orchard, the cultivars had significant effects on the rhizosphere bacterial community structure, but the age of the trees had little effects.