NOVELTY - Biological organic fertilizer comprises: fertilizer-type organic matters, e.g. industrial-, agricultural waste, grass carbon and/or humic acid; organic compound, e.g. amino acid, sugar and/or vitamin; inorganic compound, e.g. inorganic nitrogen fertilizers, phosphatic fertilizer, potassic fertilizer, calcium fertilizer, magnesium fertilizer, sulfur fertilizer, copper fertilizer, zinc fertilizer, molybdenum-, iron- and/or boron fertilizer; sulfuric acid; sour ripening powder; deodorant and biological bacterial liquid comprising Azotobacter, phosphobacteria and/or potassium bacteria.    USE - The biological organic fertilizer is useful for peach trees.    ADVANTAGE - The biological organic fertilizer improves fruit setting rate, average weight of single fruit, yield and quality factor of peach trees and reduces the content of titratable acid to increase economic benefits of the farmers.    DETAILED DESCRIPTION - Biological organic fertilizer comprises (in parts by weight) fertilizer-type organic matters (15-85), organic compound (0-30), inorganic compound (0-50), sulfuric acid (0-10), sour ripening powder (0-2), deodorant (0-2) and a biological bacterial liquid (5-35), where the fertilizer-type organic matters is industrial wastes, agricultural wastes, grass carbon and/or humic acid, the organic compound is amino acid, sugar and/or vitamin, the inorganic compound is inorganic nitrogen fertilizer, phosphatic fertilizer, potassic fertilizer, calcium fertilizer, magnesium fertilizer, sulfur fertilizer, copper fertilizer, zinc fertilizer, molybdenum fertilizer, iron fertilizer and/or boron fertilizer and the biological bacterial liquid is Azotobacter, phosphobacteria and/or potassium bacteria. An INDEPENDENT CLAIM is also included for preparing the biological organic fertilizer, comprising: (i) cultivating bacterial strains in a culture medium using the known method, sorting and culturing the strains to obtain the biological bacterial liquid; (ii) fermenting, drying and crushing the fertilizer-type organic matters; (iii) mixing the inorganic compound, sulfuric acid, sour ripening powder, the deodorant and the biological bacterial liquid; and (iv) adding the organic compound, mixing and stirring the products of the above steps (i), (ii) and(iii), extruding and granulating using a multi-roll granulator, measuring and packaging to obtain the finished products.