Abstract: An optimal extraction condition of water- soluble protein from lentinus edodes stems in alkalescency was studied and the isoelectric point and molecular weight of this protein were measured as well. The results showed that the best extraction conditions of water- soluble protein from lentinus edodes stems,solvent ratio,extraction time and extraction temperature,were 1 ∶ 28,6h and 24℃ respectively,and the ratio of this protein extraction was52.8% under the above conditions.SDS- PAGE electrophoretic analysis result indicated that the molecular weight of protein subunit bands are larger and concentrated in about 40 ~ 50 ku. The isoelectric point of the water- soluble protein in lentinus edodes stems was p H4.3,close to that of most plant proteins.