Objective:To study whether parathyroid hormone regulates the differentiation of bone mesenchymal stem cells into osteoblasts through Notch signaling pathway. Methods:Six PTH+/+ and six PTH-/- mice of 8-week-old were used in this study. Bone mesenchymal stem cells obtained from mouse femurs were isolated and cultured,then osteogenic differentiation was induced. Western blot was performed to detect the expression of Notch signaling pathway at day 3,7,10,14. The alkaline phosphate (ALP)activity was detected to evaluate the early osteogentic differentiation at day 3 and 7. Western blot was performed to detect the expression of Runx2 and OCN proteins. Results:The receptor and ligand of Notch signal pathway and the osteogenic index was increased in the wild type group and PTH gene knockout group after osteogenic differentiation. The expression of Jagged1 and Notch1 protein in PTH gene knockout group was significantly lower than that of the wild type group (P < 0.01). Compared with the wild type group,Runx2 and OCN protein levels were lower in PTH gene knockout group,with the same trends as ALP results. Conclusion:The deficiency of endogenous PTH inhibited the differentiation of bone marrow mesenchymal stem cells into osteoblasts,by reducing the expression of Notch1 and Jagged1 proteins.