The effects of potassium feldspar soil conditioner combined with different dosage of Bacillus mucilaginosus on the root growth of CB-1 flue-cured tobacco and the bacterial diversity and community structure in the rhizosphere soil of fluecured tobacco were explored，so as to provide reference for soil improvement and soil microecological environment quality improvement in Changting tobacco-growing area. Using field experiment and high-throughput sequencing technology，the root development，rhizosphere soil physical and chemical properties，enzyme activities，microbial community structure and function of flue-cured tobacco with different dosage of Bacillus mucilaginosus（T1，T2 and T3 treatments），potassium feldspar soil conditioner（T4 treatment）and potassium feldspar soil conditioner combined with different dosage of Bacillus mucilaginosus（T5，T6 and T7 treatments）were analyzed. Compared with conventional fertilization（CK），single or mixed application of potassium feldspar soil conditioner and microbial inoculum could effectively improve root activity and root morphology of flue-cured tobacco，and the effects of T6 and T7 treatments were significant. The pH of soil in each treatment was gradually increased，the contents of organic matter，alkali-hydrolyzable nitrogen and available phosphorus were all increased first and then decreased，and reached the maximum in the prosperous period. The content of available potassium gradually was decreased to the topping stage and slowly increased，and the content of available potassium in T6 and T7 treatments was higher in different growth stages. The contents of nitrate reductase，urease，sucrase and catalase in different treatments all reached the maximum in the flourishing period，and the enzyme activity in T6 treatment was the highest. The application of microbial agents could improve the abundance and diversity index of rhizosphere soil microbial community. In T2 and T6 treatments，Sideroxydans， MBNT15 and BSV26 were the dominant bacteria，with the abundance of 3.70%，3.51%，3.25% and 3.89%，3.26% and 3.21% respectively. In the analysis of Alpha diversity of bacterial community，the order of Shannon index，Simpson index，Chao1 index，Ace index and PD index of each treatment was T6 ＞ T2 ＞ T4 ＞ CK. Potassium feldspar soil conditioner and microbial inoculum can promote the root development of flue-cured tobacco，improve that nutrient and enzyme activity of rhizosphere soil， increase soil bacterial diversity and improve microbial community structure. Among them，T6 treatment showed the best effect.