The invention relates to the technical field of biology, particularly a method for producing an organic fertilizer from Flammulina velutipes Italian poplar mushroom residues. Many methods for fermenting organic fertilizers by using Flammulina velutipes mushroom residues of miscellaneous wood dust or corn cobs exist, but no method for fermenting organic fertilizers by mainly using Flammulina velutipes mushroom residues containing Italian poplar wood dust is reported. The method comprises the following steps: proportionally mixing Italian poplar wood dust Flammulina velutipes mushroom residues with rice bran, wheat bran and the like to prepare a fermentation culture medium, inoculating an activated rotting microbial inoculant, fermenting at the temperature of higher than 35 DEG C for 30 days, finishing fermentation when the mushroom residues become dark brown, removing the pile, and drying the organic fertilizer in the shade until the water content is lower than 30%. The method greatly lowers the production cost of the organic fertilizer, and converts the edible fungus culture waste into the fertilizer, thereby achieving the effect of circulating growth.