NOVELTY - Preparing diosgenin by solid state fermentation using combination of microorganisms involves culturing Trichoderma reesei, T.viride and Aspergillus fumigatus separately in culture mediums containing turmeric extract, storing in preservation medium, preparing turmeric residue, inoculating stored strains in activation culture mediums, inoculating T.viride, fermenting for specific time period, inoculating T.reesei, continuing fermentation, inoculating A.fumigatus and extracting fermented product with organic solvent.    USE - The method is useful for preparing diosgenin by solid state fermentation of turmeric extract using combination of microorganisms (claimed).    ADVANTAGE - The method is simple and environmentally-friendly, and increases microbial fermentation efficiency and diosgenin production rate.    DETAILED DESCRIPTION - Method for preparing diosgenin by solid state fermentation using combination of microorganisms involves (a) several times culturing Trichoderma reesei, T.viride and Aspergillus fumigatus in their respective culture mediums containing low concentration ethanol extract of turmeric for obtaining pure mold spores, then culturing obtained mold spores of 3 microorganisms in separate culture mediums containing high concentration ethanol extract of turmeric and finally storing obtained strains in preservation medium containing 50% ethanol extract of turmeric; (b) washing raw turmeric, drying and crushing washed turmeric, sieving crushed powder, removing starch, crushing and sieving again to obtain turmeric residue; (c) inoculating stored strains in activation culture mediums to obtain their respective active mother cultures; (d) inoculating T.reesei strain obtained from the mother culture in fermentation medium containing turmeric residue, fermenting for specific time period, then inoculating T.viride, continuing fermentation, finally inoculating A.fumigatus and fermenting to obtain fermented product; and (e) filtering and drying fermented product, extracting with organic solvent, and crystallizing extract to obtain the product.