The invention discloses a preparation method of a dendrobium officinale fungus fermented product, the fermented product and an application of the fermented product. The preparation method of the dendrobium officinale fungus fermented product includes the steps of dendrobium officinale preparation, strain activation, liquid seed culture, dendrobium officinale fungus fermentation and fermented product processing. The fermented product is obtained by the preparation method of the dendrobium officinale fungus fermented product. The application comprises that the dendrobium officinale fungus fermented product is used for preparing food, health food, cosmetics and / or drugs. Dendrobium officinale is fermented with medicinal and edible fungi containing cellulose and other substances, dendrobium cellulose and the like are decomposed into small-molecular carbon sources, and the beneficial ingredients of the dendrobium officinale are retained; and moreover, the fermented product has mellow mouthfeel, has both faint scent of the dendrobium officinale and unique flavor of the fungi, also is rich in fungal polysaccharides, saponins, polyphenols, flavonoids and other active substances; the effective ingredients are easily absorbed in intestines, and has the efficacies of improving immunity, resisting tumor, resisting oxidation, reducing blood fat and blood pressure, regulating the balance ofintestinal microflora and the like.