Abstract: The mechanism of soil microbial community assembly and succession has always been the research hotspot of microbial ecology, the core of biodiversity and life community research, and the basis of scientific management of soil microorganisms. It is of great significance to fully utilize soil microbial resources. We systematically reviewed the basic theory of soil microbial community assembly, analyze the factors affecting the balance between deterministic and stochastic processes of microbial community assembly, compare the similarities and differences in the assembly process of soil microbial communities in natural and farmland ecosystems. Finally, we look forward to the application potential of the theory and methods of microbial community assembly in farmland ecosystem, which provides an important scientific basis for improving soil quality of farmland and the function of soil ecosystem.