NOVELTY - Bio-organic fertilizer preparation involves using (in parts): fresh cow dung (40-50), semi-dried cow dung (40-50), calcium superphosphate (3-6), trace element (0.1-1), fermentation agent A (0.1-0.2) and fermentation agent B (0.1-0.2), where water content in fresh cow dung is greater than or equal to 80%. The semi-dried cow dung has 40-50% of water content. The trace element comprises iron, zinc, manganese, boron, molybdenum and copper. The fermentation agent A is composed of Lactobacillus acidophilus, Saccharomycetes and Bacillus subtilis in a weight ratio of 1:1:1.    USE - Method for preparing bio-organic fertilizer (claimed).    ADVANTAGE - The method provides the bio-organic fertilizer easily by using and recycling organic wastes in a simple, safe, cost-effective and eco-friendly manner.    DETAILED DESCRIPTION - Bio-organic fertilizer preparation involves using (in parts): fresh cow dung (40-50), semi-dried cow dung (40-50), calcium superphosphate (3-6), trace element (0.1-1), fermentation agent A (0.1-0.2) and fermentation agent B (0.1-0.2), where water content in fresh cow dung is greater than or equal to 80%. The semi-dried cow dung has 40-50% of water content. The trace element comprises iron, zinc, manganese, boron, molybdenum and copper. The fermentation agent A is composed of Lactobacillus acidophilus, Saccharomycetes and Bacillus subtilis in a weight ratio of 1:1:1. The fermentation agent B is composed of round brown ammonia bacteria and Bacillus megaterium in a weight ratio of 1:1. The bio-organic fertilizer is prepared by mixing fresh cow dung with semi-dried cow dung uniformly, where calcium superphosphate powder is added to the mixture. Fermentation agent A is sprayed on the mixture, where the mixture is overturned uniformly once in a day by an overturning machine to form a trapezoidal long stack (1m height, 2m width) on cement ground. Water is added to fermentation agent B to prepare spray solution, which is sprayed on cow dung stack (40% moisture content). The stack is overturned once in a day by an overturning machine. Trace element is added to the stack (30% moisture content) and then the stack is overturned uniformly by an overturning machine. The stack is stored in an after-ripening storeroom, where the stack is overturned once in a week. The stack is stored in storeroom at constant room temperature. The fertilizer is pulverized and packaged to obtain the finished product.