Soil health is an important prerequisite to ensuring food security and maintain the services and functions of terrestrial ecosystems. Soil microorganisms play a key role in regulating nutrient circulation, enhancing rhizosphere immunity, and preventing environmental pollution. Rational development and application of microbial resources is an important means to protect soil health and exert soil functions in the future. However, the heterogeneity and complexity of soil ecosystems limit the identification and utilization of microbial functions. Currently, the development of synthetic biology provides new ways and ideas for using microorganisms to promote soil health. By fully exploiting the metabolic diversity, functional stability, environmental adaptability of microbial communities, and rationally constructing synthetic communities, technical support can be provided for the ecological restoration of soil damaged by environmental pollution or degraded in quality due to agricultural use. This review summarizes the approaches, tools, and application scenarios for constructing synthetic communities and explores their mechanisms in remediating contaminated soils, enhancing soil fertility, and promoting plant resistance to soil-borne diseases and abiotic stresses. Furthermore, future research directions are proposed, including the construction of synthetic community repositories, the development of synthetic biology tools, and the application of artificial intelligence for screening synthetic communities. These strategies are of great significance for achieving precise construction and directional utilization of synthetic communities in a specific range to improve soil health and ensure sustainable use of soil.