The present invention relates to a preparation method of solid-state and multi-microorganism citric acid acidized fermented feed. Clean water, starch materials, fruits and vegetables, products containing sugar, molasses syrup, fiber materials, bean cake and meal products, food processed by-products and nutrition accessory materials are mixed proportionally, the mixture is sterilized using a high temperature, the sterilized mixture is cooled, strains producing citric acids are inoculated to conduct a solid fermentation for several hours, and a citric acid solid fermentation medium wet base is prepared. Clean water, feed raw materials, compound microorganism strains and compound enzymes are mixed to conduct enzymolysis and fermentation for several hours to obtain a fermented feed wet base. The citric acid solid fermentation medium wet base, fermented feed wet base and one or more of feed use inorganic acids, organic acid salts, saccharides, oil, Chinese herbal medicines and vitamins are mixed, and the mixture is dried to obtain the solid-state and multi-microorganism citric acid acidized fermented feed. The prepared feed contains citric acids, proteins, crude fibers and other nutrients, and has characteristics of preventing diarrhea, being good in palatability, easily digestible, etc.