Abstract: 【Objective】 To preliminarily identify the soil microecological mechanism of tobacco straw biomass carbonbased fertilizer to improve the growth of tobacco plants, and provide necessary theoretical support and practical experience for the environmental effect assessment and scientific application of tobacco straw biochar.【Method】 In the field experiment, the conventional fertilization without tobacco stalk biochar-based fertilizer was used as the control, and three biocharbased fertilizer treatments were set up(2700,3375 and 4050 kg/ha). The incidence of major diseases and disease index were measured 60 d after transplanting. The maximum net photosynthetic rate of functional leaves was measured 90 d after transplanting. After roasting, soil samples were collected to determine physical and chemical properties and to analyze soil bacterial community structure.【Result】Compared with the control, the application of tobacco straw biochar-based fertilizer significantly increased the net photosynthetic rate of tobacco leaves(P<0.05), and reduced the degree of disease harm to different degrees. At the same time, the soil pH, contents of total potassium, total nitrogen, hydrolyzable nitrogen and organic matter were increased to different degrees. There was no significant difference in the α diversity index of soil bacteria(P>0.05),but the Chao1 and ACE indexes of soil bacteria in the treatment of tobacco straw biochar-based fertilizer were decreased,and the Shannon and Simpson indexes were increased,and the community structure was obviously separated. The species composition analysis of bacterial communities showed that the relative abundances of Anaeromyxobacter and Geobacter increased greatly. Variance decomposition analysis and redundancy analysis showed that soil physical and chemical properties were closely related to microbial communities,and organic matter and hydrolyzed nitrogen contributed the most to community distribution. FAPROTAX function prediction showed that the potential functions of soil bacteria were more abundant and diversified after the application of tobacco straw biochar-based fertilizer.【Conclusion】Tobacco straw biochar-based fertilizer may have a positive effect on flue-cured tobacco growth and development by regulating soil physicochemical properties and improving soil bacterial community structure and function, and Anaeromyxobacter and Geobacter may play an important role.