Preparation method of feed additive capable of improving animal immunocompetence

The invention relates to the technical field of feed additives, and discloses a preparation method of a feed additive capable of improving animal immunocompetence. The preparation method comprises the following steps: S1, preparing calcium lactate: adding lactic acid and calcium carbonate into a mixing tank for mixing, adding citric acid, ferrous fumarate and fumaric acid during mixing, and fermenting to prepare calcium lactate; s2, coating with an acidifying agent; s3, culturing materials, separating and purifying licheniformis spores and lactic acid spores, and then culturing the licheniformis spores and lactic acid spores; and S4, strain amplification: planting endogenous lactobacillus acidophilus and bacillus subtilis strains in the culture solution, and carrying out amplification treatment. The problem that antibiotics are abused for preventing and treating common diseases and frequently-occurring diseases at present is solved, the safety of livestock and poultry products is greatly improved, the ever-in