The invention discloses a biological fermentation fertilizer and a preparation method of the biological fermentation fertilizer. The biological fermentation fertilizer consists of mountain soil, soil modifying agents, rice bran, starch and enzyme microorganism according to a certain proportion. The preparation method comprises the following steps of A, starch or brown sugar, rice bran, enzyme microorganism and mountain soil preparation; B, material mixing: a, the starch or the brown sugar is dissolved by water and is uniformly spread on mixed raw materials of the rice bran and the enzyme microorganism, and the stirring is carried out while spreading; b, the mountain soil is added, and in addition, water is added to regulate the water content to be 45 percent; and c, a clean mat is used for covering; C, pile turning: the pile turning is carried out each day; D, fermentation: the fermentation is completed; E, drying: the materials are spread into thin layers on the cement ground for natural drying; F, inspection; and G, package. The biological fermentation fertilizer and the preparation method have the advantages that the product recipe is reasonable, the method is easy to implement, the operation is simple and convenient, beneficial microorganism floras are conveyed to soil cultivation layers, the ecological environment of the soil is improved, the physical and chemical properties of the soil are improved, the crop growth is promoted, the crop quality is improved, the fertilizer consumption is reduced, and the cost is saved.