Abstract: Agaricus bisporus protein powder was obtained by spray drying method. Based on the single factor experiment, orthogonal experiments were carried out on the inlet air temperature, the concentration of protein liquid and the feeding velocity. The experiment results showed that when the inlet air temperature was 165℃, the protein concentration was 40 mg/mL and the feeding velocity was 650 mL/h, the powder collection rate was 38.8%. The protein powder was creamy in milk and fragrant in fresh mushrooms. Nutritional analysis showed that protein powder contains protein, carbohydrate, crude fat, crude fiber, ash and moisture was 65.8%, 8.8%, 0.4%, 3.8%, 2.0%, 7.20%;Amino acids preparation was abundant 8 kinds of essential amino acids account for 41% of the total amino acid. Four essential amino acids, such as isoleucine, threonine, lysine, tryptophan was closed to the FAO/WHO standard. In addition, it contained abundant mineral elements. The heavy metals such as cadmium, lead, arsenic and mercury content were in line with the national standard of food safety.