Abstract: To clarify the regulatory effects of root drenching with microbial inoculants on the growth and development of flue-cured tobacco, tobacco leaf quality and metabolic characteristics of rhizosphere soil, a field experiment was conducted in Wushan County, Chongqing City. Two treatments were set up, namely microbial inoculant root drenching(M) and clear water control(CK). The effects of different treatments on agronomic traits, economic traits, appearance quality and chemical components of flue-cured tobacco were systematically investigated, and untargeted metabolomics technology was adopted to analyze the metabolic differences in rhizosphere soil. The results showed that compared with CK, treatment M promoted the growth of tobacco plants, and significantly increased plant height, stem girth, as well as leaf length and width of upper, middle and lower leaves. Meanwhile, it improved economic traits including tobacco leaf yield, output value and the proportion of superior-grade tobacco leaves. The cured tobacco leaves presented orange-yellow color and sufficient oil content in appearance quality. The coordination of key chemical components such as total nitrogen, nicotine and reducing sugar, as well as sensory quality indicators including aroma quality, mellow smoke taste and comfortable aftertaste were obviously improved. Metabolomics analysis revealed that treatment M altered the metabolic profile of flue-cured tobacco rhizosphere soil. A total of 12 significantly differential metabolites were identified, among which 8 were up-regulated and 4 were down-regulated. These metabolites were mainly enriched in metabolic pathways including glycolysis/gluconeogenesis, pentose phosphate pathway, amino acid metabolism and ABC transporters, which facilitated soil carbon source activation and nitrogen mineralization and optimized soil carbon and nitrogen nutrient cycling. In conclusion, root drenching with microbial inoculants can effectively promote tobacco plant growth and improve tobacco leaf quality by regulating rhizosphere soil metabolic characteristics and optimizing carbon and nitrogen nutrient supply, which provides a feasible technical support for high-quality flue-cured tobacco production.