The invention relates to a method for producing a high-efficiency composite microbial agent by using livestock liquid dung, and belongs to the technical field of environmental microbiology and agricultural science. The method comprises the following steps: diluting livestock liquid dung or livestock feces with water; after hydrolysis and acidification treatment, performing standing and settlement for desilting; mixing a supernatant obtained with a photosynthetic bacterial solution for anaerobic culture; using the mixed solution as a base liquid and stepwise adding lactobacilli, saccharomyces, bacillus thuringienesis and actinomycete into the base liquid in a proportion; and after anaerobic culture and aerobic treatment, finally filling the mixture into a biological fluidized bed for further treatment to obtain the high-efficiency composite microbial agent. The microbial agent is rich in the photosynthetic bacteria, the lactobacilli, the saccharomyces, the actinomycete, the bacillus thuringienesis, azotobacter, nitrobacteria, denitrifying bacteria and other beneficial organisms, and be widely used in agriculture, livestock breeding, fresh water aquaculture, organic sewage treatment, microbial deodorization, and other aspects. The technology is suitable to be used by various livestock farms (raisers) for liquid dung treatment.