The invention provides a microbiological composite bacterial agent and an application thereof in adjusting soil pH value. The bacterial agent comprises the following active components: bacillus, lactobacillus, saccharomycetes, soil actinomycetes, and mycete. The bacterial agent can adjust soil pH value, establishes a good crop rhizosphere micro-ecological environment, loosens the soil, increases the air permeability, improves the water-retention and fertilizer conservation performance of the soil, helps to form dominant bacterial communities of beneficial bacteria, effectively inhibits the growth of pathogenic microorganism, relieves the soil borne diseases, strengthens the anti-disease performance of crops, maintains the soil micro-ecological system and ecological balance, modulates the soil structure, improves the crop rhizosphere soil micro-ecological system, promotes the crop to grow roots, increases the crop output, improves the product quality, increases the microorganism content and trace element content in soil, and thus achieves the goals of improving physical and chemical properties of soil, strengthening the water-retention and fertilizer conservation performance of the soil, and increasing the air permeability of the soil. The microbiological composite bacterial agent has the advantages of user-friendliness, low cost, and prominent effect, can prevent the happening of insects and diseases, and improves the product output and quality.