Abstract: The extraction conditions of protein from Agaricus bisporus by alkali dissolution and acid precipitation method was optimized by response surface methodology. The amino acid contents and functional properties of Agaricus bisporus were studied. The results showed that,the maximum extraction rate of protein was obtained after extraction at 57 ℃ and pH9.9 with a solid-to-solvent of 1:3 (g/mL)for 2.6 h,and the protein recovery rate was 60.29%±0.19%,the purity was 72.70%±0.38%.The ratio of essential amino acid contents to non-essential amino acid contents of Agaricus bisporus protein was 0.776,which was higher than the World Health Organization's specified value of 0.666. The lowest solubility of Agaricus bisporus protein was 17.18% at pH4.0. When the pH was 7.0,the water holding capacity,foaming capacity,bubble stability,oil holding capacity,emulsifying capacity,and emulsifying stability of Agaricus bisporus protein were 705.00%±5.06%,80.04%±0.54%,55.41%±0.09%,518.00%±2.06%,17.81%±0.02% and 10.11%±0.0% respectively. The water-holding and oil-holding properties of the Agaricus bisporus protein were higher than that of the soy protein isolate(495.00%±3.18% and 210.29%±1.59%). In summary,Response Surface Methodology(RSM)optimization of Agaricus bisporus protein technology was reasonable and feasible. Agaricus bisporus protein would be a high quality protein that can be developed.