Abstract: The polysaccharidess was extracted from Morinda officinalis How by enzyme-assisted extraction. The physicochemical properties of polysaccharides such as pH,relative viscosity,solubility,spectral characteristics and spatial conformation were studied by chemical and instrumental analysis.The proliferation rate of MC3T3-E1 cells was determined by Thiazolyl Blue Tetrazolium Bromide(MTT)assay,and the secretion of collagen type(COLⅠ),alkaline phosphatase(ALP)and osteocalcin(OCN)were detected by enzyme-linked immunosorbent assay(ELISA).The effect of polysaccharide on the proliferation of osteoblasts was evaluated. The results showed that the polysaccharide of Morinda officinalis How belonged to acidic polysaccharide with pH of 6.15±0.13,relative viscosity of 1.26±0.12,which had sugar characteristics and triple helix structure;had good solubility and did not contain protein or polypeptide. When the extract concentration of Morinda officinalis How polysaccharide was 50 μg/mL,the proliferation rate of MC3T3-E1 cells increased significantly(P<0.01),to 149.67%,the secretion of COL I and OCN increased significantly(P<0.01),increased by 44.98% and 85.01% respectively,and the activity of ALP increased significantly(P<0.01),and increased by 258.95%. These indicated that polysaccharide extracted from Morinda officinalis How could significantly promote the proliferation and differentiation of MC3T3-E1 cells.