The invention discloses a preservation method which is suitable for storing edible mushroom. According to the preservation method, a natural preservation agent chitosan is dissolved in water to obtain an aqueous solution, the aqueous solution is sprayed on the surface of edible mushroom to form a film, thereby postponing aging process, reducing loss of nutrients such as sugars, organic acid, vitamin C and the like caused by a respiration, and inhibiting breeding of harmful bacteria; moreover, in conjunction with the modified atmosphere packaging (MAP) technology, two methods achieve synergistic effect, thereby achieving obvious edible mushroom preservation effect. Contrast experiments shown that in comparison with edible mushroom not subjected to any treatment, pleurotus eryngii and Griflola frondosa stored by the preservation method have the advantages of bright surface, high freshness, no objectional odor or brown stain, low nutrient loss and remarkable preservation effect. The preservation method is easy to popularize and apply, capable of prolonging shelf life, thereby achieving a purpose of preservation and storing edible mushroom for a long term.