Objective To study the effect of silicon-doped hydroxyapatite (Si-HA), which is prepared in accordance with the silicon content in natural bone, on the activity of osteoblasts. Methods Hydrothermal synthesis method was used to prepare hydroxyapatite doped by microdosage silicon. The surface of the material was observed by X-ray diffraction (XRD) and scanning electron microscope. MG63 osteoblast-like cells were cultured on the surface of materials for 1, 6, 12 h and 1, 4, 7, 14 d, respectively; then the adhesion and proliferation of MG63 cells were detected by CCK8 method; and the number of cell adhesion was verified by DAPI staining. Alkaline phosphatase (ALP) activity of the MG63 cells was assessed with ALP assay kit; RT-PCR was used to detect the expression of osteoblast specific genes (ALP, Collagen Ⅰ and osteocalcin) at 1, 4, 7, and 14 d. Results The surface structure and composition of hydroxyapatite were not changed by Si. After cultured for 6 and 12 h, the MG63 cells adhered to Si-HA surface was significantly more than that to HA surface (P<0.05), which was consistent with the findings of DAPI staining. After cultured for 4 and 7 d, the number of cells on Si-HA surface increased significantly compared with that on HA surface(P<0.05). ALP activity in cells cultured on Si-HA surface were significantly higher than those on HA surface (P<0.05); the expression of CollagenⅠgene in Si-HA group was significantly higher than that in HA group on day 4, 7, and 14(P<0.05), and the expression of osteocalcin gene was significantly higher on day 7 and 14(P<0.05). Conclusion Silicon-doped hydroxyapatite in accordance with silicon content in the natural bone can promote the adhesion, proliferation and the expression of osteogenic specific genes of osteoblast MG63 cells, indicating that the prepared material has an improved biological activity compared with pure HA.