The invention discloses a processing method of mushroom extract powder, which comprises the following steps: drying and crushing a fresh mushroom to obtain the mushroom extract powder; adding the mushroom extract powder into water to obtain mushroom extract powder solution; respectively adding common salt, dextrin, beta-cyclodextrin and glucose into the mushroom extract powder solution to obtain mixed solution; placing the mixed solution into a homogenizer to obtain homogenized solution; and adding the homogenized solution into a reaction kettle for three-time temperature raising, spraying, drying and collecting to obtain the mushroom extract powder. Since the common salt, the dextrin, the beta-cyclodextrin, the glucose and other auxiliary materials are added to carry out a maillard reaction with the mushroom extract powder solution, on one hand, products have uniform texture and favorable solubility; and on the other hand, the flavor of the products can be increased; meanwhile, powder is sprayed by adopting a spray drying method, the method has the advantages of high drying speed and short heated time of products; and in addition, by adding dextrin at early stage and the beta-cyclodextrin and using the maillard reaction, nutrient contents of the mushroom can be effectively protected and the damage at minimum extent to the nutrient contents of the mushroom in the powder spraying process can be ensured.