The changes of microbial biomass carbon，microbial biomass nitrogen，microbial diversity，microbial community structure and driving factors were analyzed in four different years including Y1 （flue-cured tobacco planting 1 a），Y2 （flue-cured tobacco continuous cropping 3 a），Y3 （flue-cured tobacco continuous cropping 5 a） and Y4 （flue-cured tobacco continuous cropping 7 a） of tobacco planting soils in Shangluo area，the hinterland of Qinling Mountains to study the changing characteristics and driving factors of microbial community structure of flue-cured tobacco soil under different continuous cropping conditions.The results showed that the microbial biomass carbon，nitrogen and carbon nitrogen ratio decreased with the increase of planting years，with the decrease of 37.16%，20.40% and 21.10%，respectively.The abundance and diversity of bacteria in soil decreased significantly.The dominant bacteria were Actinobacteriota，Proteobacteria，Chloroflexi，Acidobacteriota and Firmicutes，with the total relative abundance accounting for 80% or more.The abundance of fungi in soil increased significantly.The dominant fungi were Ascomycota，Basidiomycota and Mucoromycota，with the total relative abundance accounting for 90% or more.Under the condition of Y4 continuous cropping，the relative abundance of beneficial microorganisms such as Firmicutes and Desulfobacterota in the soil decreased.The relative abundance of pathogenic microorganisms such as Mucoromycota and Chytridiomycota increased.Long term continuous cropping will reduce the relative abundance of beneficial microorganisms in soil，increase the relative abundance of pathogenic microorganisms，and decrease the carbon nitrogen ratio of soil microbial biomass，thereby increase the risk of tobacco disease.Therefore，the establishment of a good farming system or the construction of microbial community is the key technical way to alleviate or solve the imbalance of microbial community structure in continuous cropping tobacco fields.