The invention provides a complex microbial agent for stabilizing treatment of stock garbage in cities and towns as well as a preparation method and an application of the complex microbial agent. The complex microbial agent contains sporotrichum thermophile, pseudomonas alcaligenes, halobacillus sp, bacillus subtilis, pseudomonas putida, candida utilis, saccharomyces cerevisiae, phanerochaete chrysosporium and lactobacillus plantarum. Growth metabolism, degradability and activity of all microbial strains in the complex microbial agent can effectively complement and cooperate with one another, the microbial strains can grow and propagate quickly in a landfill system to promote the temperature of a garbage treatment environment to increase quickly, meanwhile, organic matter, BDM and toxic andharmful substances in a landfill can be quickly and efficiently degraded, the stabilizing time of the garbage landfill is greatly shortened, stable harmless treatment of landfill is promoted, and thecomplex microbial agent can be applied to aerobic stabilizing treatment of garbage in cities and towns in practice.