Abstract: To clarify the characteristics of leaf structure and phyllosphere microbial morphology, carbon source metabolic capacity, and community structure diversity for tobacco leaves affected by wildfire disease, scanning electron microscopy, BIOLOG ECO, and Illumina NovaSeq high-throughput sequencing technologies were used to investigate the differences in leaf structure, phyllosphere bacteria and fungal communities between infected and healthy tobacco leaves. The results showed that a significant number of bacterial hyphae, fungal hyphae, and spores adhered to the surfaces of infected tobacco leaves that were severely damaged. The phyllosphere microbial communities of the infected tobacco leaves had the highest utilization capacity for carboxylic acids (methyl pyruvate and D-malate, etc.), whereas those of healthy tobacco leaves had the highest utilization capacity for polymers (Tween-40 and Tween-80, etc.). Both leaf groups were inefficient in the utilization of phenolic compounds (2-hydroxybenzoic acid and 4-hydroxybenzoic acid). Although no significant differences were observed in the phyllosphere bacterial and fungal communities between the infected and healthy tobacco leaves at phylum level, significant differences were observed at the genus level. Dominant bacterial genera of the infected tobacco leaves were Pseudomonas (67.43%) and Pantoea (5.75%), whereas Ralstonia (17.62%), Pseudomonas (15.79%) and Ruminobacter (12.76%) dominated in the healthy samples. Dominant fungal genera were Phoma (24.68%), Alternaria (22.87%) and Phialocephala (5.72%) on the infected tobacco leaves, whereas Cladosporium (14.80%), Sampaiozyma (8.19%) and Mortierella (5.23%) on the healthy tobacco leaves. Significant differences in diversity and richness between phyllosphere bacterial and fungal communities of the infected and healthy tobacco leaves indicated that a composite infection of bacteria such as Pseudomonas spp. and fungi such as Phoma spp. contributed to the progression of tobacco wildfire disease.