A microbial fermentation method for improving tobacco quality comprises the following steps: (1) taking flue-cured tobacco as an inoculation source, inoculating the flue-cured tobacco into a tobacco powder culture medium, and culturing at 20-40 DEG C for 20-50 hours; (2) inoculating the bacterial liquid in the step (1) into a fresh tobacco powder culture medium, culturing at 20-40 DEG C for 20-50 hours, and circulating for 15-25 cycles to obtain a stable flue-cured tobacco microbial flora; (3) inoculating the microbial flora obtained in the step (2) into a fresh tobacco powder culture medium, and culturing at 20-40 DEG C for 20-50 hours to obtain a seed solution of the microbial flora; (4) centrifuging the bacterial liquid obtained in the step (3) and collecting thalli; (5) washing the thalli collected in the step (4); (6) resuspending the thalli washed in the step (5) to obtain a bacterial suspension; and (7) spraying the bacterial suspension in the step (6) on the tobacco leaves, and fermenting for 6-8 days. The microbial flora enriched and domesticated from the flue-cured tobacco is used for tobacco leaf fermentation, and the tobacco quality can be improved in multiple aspects.