NOVELTY - Method for preparing composition for cultivating Grifola frondosa, involves immersing shiitake mushroom powder in purified water, extracting mixture, mixing extract with bagasse, sawdust and bean cake, stirring and stacking mixture, naturally fermenting the mixture, turning the mixture during fermentation, adding lime and gypsum, continuously fermenting mixture, packaging the fermented product in a polypropylene plastic bag, inoculating the G.frondosa into fermented product, cultivating the G.frondosa and performing fruiting management.    USE - The method is useful for preparing composition which is used for cultivating G.frondosa (claimed).    ADVANTAGE - The method prepares composition which is rich in nutritional components e.g. sugars, amino acid, peptide, nucleic acid and trace elements, saves labor, and is environmentally-friendly to perform. The composition exhibits antibacterial effect.    DETAILED DESCRIPTION - Method for preparing composition for cultivating Grifola frondosa, involves (a) obtaining 37-45 %mass bagasse, 36-44 %mass sawdust, 10-12 %mass bean cake, 3-4 %mass shiitake mushroom residues, 3-4 %mass lime and 1 %mass gypsum with respect to 100 %mass of the composition, crushing the bagasse to obtain powder having particle diameter of 3-5 mm, crushing the sawdust to obtain powder having particle diameter of 3-5 mm, and drying and crushing the shiitake mushroom residues to obtain powder having particle diameter of 2-3 mm, (b) immersing the shiitake mushroom powder in 20-30 times purified water at room temperature for 18-24 hours, extracting obtained mixture, uniformly mixing extract with the bagasse, sawdust and bean cake, stirring obtained mixture, stacking the mixture to a height of 1-1.2 m and width of 2-3 m, maintaining dry weight of the mixture at 300-500 kg, and naturally fermenting the mixture for 24 hours, (c) turning the mixture during fermentation when the mixture reaches 60 degrees C, adding lime and gypsum, continuously fermenting mixture for 5-6 days, and controlling moisture content of fermented product at 63-65%, and (d) packaging the fermented product in a polypropylene plastic bag having size of 17 cmx 35 cmx 0.004 cm, providing holes in the bag, inoculating the G.frondosa into the fermented product, cultivating the G.frondosa at 18-20 degrees C for 22-23 days until the bag is covered with mycelium, controlling humidity at 60-75% during cultivation, and performing fruiting management.