Abstract: The effects of different particle size on composition properties, nutrition of amino acids andtotal sugar content in stipe base of Pleurotus eryngii were studied.The results showed that crude protein mass fraction was all about 20% and decreased with the powder particle size became smaller for different particle sizes ( p < 0.01) , but no difference between 200 meshes and 300 meshes ( p > 0.05) .Amino acid mass fraction of Glu was the highest, followed by Asp, the lowest in His.Flavor amino acid, antioxidant amino acid and branched- chain amino acids accounted for about 50%, 30% and 16% of total amino acids ( TAA) , respectively.The ratio of branched- chain amino acids to aromatic amino acids was about 2.Val was the first limiting amino acid.Compared with FAO /WHO model, mass fraction of Trp and Cys + Met was higher.EAA ( Essential amino acid) /TAA and EAA /NEAA ( Nonessential amino acid) were 43% ⁴5% and 76% ⁸1%, exceeded the standard model.The mass fraction of total sugar incresed with the powder particle size became smaller, but no difference between 120 meshes and 80meshes ( p > 0.05) , 250 meshes and 200 meshes ( p > 0.05) , 300 meshes and 250 meshes ( p > 0.05) , respectively.It could conclud that amino acid composition properties and nutritional values of different particle size of Pleurotus eryngii stipe base powder were similar, while the mass fraction of total sugar were different.