The invention discloses a method for improving micromeritic characteristics of agrocybe aegerita and improving dissolution of part of nutrient substances, belonging to the technical field of processing of edible and medicinal fungus products. The method comprises the following steps: (1) pretreatment of fruit bodies of the agrocybe aegerita; (2) ultra-high pressure modification treatment; and (3)microwave extraction and the like, wherein the ultra-high pressure treatment enables texture and tissue of the agrocybe aegerita to change, increases the water retention ability and the expansion force, reduces the viscosity and also improves the dissolution of water-soluble proteins, polysaccharides and reducing sugars; and the microwave extraction enables ultra-high pressure powder proteins andthe polysaccharides to be easier to dissolve out. The method is convenient, time-saving, energy-saving, non-toxic and green and can obviously improve the extraction rate of the polysaccharides, the proteins and other nutrient substances. The method can be popularized and applied in enterprises for processing edible and medicinal fungi.