Abstract: In order to analyze the biodiversity of phyllosphere bacterial genus from tobacco leaves infected by brown spot disease in fields, DNA was extracted from diseased tobacco leaves, 16S region was amplified and sequenced. The amplified fragments were sequenced by IonS5XL high-throughput sequencing technology, and the bacterial community structure was analyzed. The results showed that the community structure of phyllosphere bacteria from tobacco leaves infected by brown spot disease was quite typical. At the phylum level, the predominant bacteria were Proteobacteria (71.59%); at the genus level, the predominant bacteria included Pantoea (31.23%), Pseudomona (22.44%), Methylobacterium (6.17%), Sphingomonas (6.02%), Aureimonas (2.08%) and Falsirhodobacter (1.35%). All these bacteria were the symbiotic bacteria from tobacco leaves infected with brown spot disease.