Plant rhizosphere microbes are closely related to plant growth, whereas how the rhizosphere microbial community affects root development remains poorly understood. In this study, 16S rRNA gene high-throughput sequencing technology was used to detect the bacterial community of tobacco rhizosphere, and to explore the association mechanism between different developmental conditions of tobacco roots and differences in rhizosphere microbial community. The results showed that the species richness and diversity of rhizosphere bacteria in the well-developed root system (WDR) were higher than those in the undeveloped root system (UDR), with the genera Gallionella and Luteimona significantly increased, while the genera Edaphobaculum, PLTA13 and Rhodobacter significantly increased. Abundance significantly reduced (P<0.05). The molecular ecological network of UDR is more complex, and the interaction between species is strong, especially the cooperative behavior. The number of key nodes in the WDR network is more, and its carbon cycle related network modules increase. In addition, the WDR rhizosphere bacterial community assembly tends to be more developmentally aggregated, and environmental filtering plays a more important role in it. Overall, the results of this study emphasize that the structural composition, network changes and community assembly of the rhizosphere microbial community play an important role in the development of plant roots, and provide a theoretical basis for regulating the rhizosphere microbial community to promote plant root growth.