The effects of lignin on the growth of flue-cured tobacco and soil microorganisms were studied to provide reference for the utilization of lignin as resources.The effects of lignin on flue-cured tobacco growth and soil microorganisms were studied in a pot experiment in which lignin with 2‰ and 5‰ of soil weight was added as the treatment groups(L2 and L3)and no lignin was added as the control group(L1).Based on the determination of flue-cured tobacco agronomic traits and soil pH，the effects of lignin on flue-cured tobacco growth and soil microorganisms were studied by high-throughput sequencing and co-occurrence network analysis.Functional groups of bacteria and fungi were analyzed using the FAPROTAX database and FUNGuild.The results showed that compared with the control treatment，the plant height of L2 and L3 treated tobacco increased by 10.1% and 15.6%，and the upper leaf length increased by 6.9% and 12.2%，respectively.The pH of soil treated with L2 and L3 decreased by 0.38 units in the early stage of maturation.Alpha diversity analysis and PCoA analysis showed that lignin addition had no significant effects on soil microbial diversity index(Shannon index)，richness index(Chao1 index)and β diversity.The analysis of microbial community composition at gate level showed that the addition of lignin significantly reduced the relative abundance of Bacteroides，blastomonas and Nitrocellulosis in early maturity and Acidobacteria in upper tobacco leaf maturity.The relative abundances of ascomycetes and basidiomycetes were significantly increased in the early and upper mature stages of tobacco leaves，while the relative abundances of mortierella were decreased.The results of microbial co-occurrence network analysis showed that lignin reduced the complexity of soil microbial co-occurrence network，increased the stability of bacterial co-occurrence network，and weakened the cooperative relationship between fungal communities.At the same time，the addition of lignin made actinomyces become one of the dominant bacterial groups in the bacterial co-occurrence network.The functional prediction results showed that the addition of lignin significantly increased the abundance of genes related to nitrate respiration and nitrogen respiration.The relative gene abundance of Animal Pathogen-Endophyte-Epiphyte-Fungal Parasite-Plant Pathogen-Wood Saprotroph was significantly reduced.Correlation analysis showed that Saccharibacteria genera incertae sedis，Gemmatimonas and Minutisphaera were positively correlated with plant height and upper leaf length at different periods，respectively.In general，the addition of lignin changed the microbial community composition in tobacco-growing soil.Among them，Saccharibacteria genera incertae sedis，Gemmatimonas and Minutisphaera may play an important role in increasing the plant height and upper leaf length of flue-cured tobacco.