To observe the inducing effects of 17β-estradiol on the differentiation of bone marrow mesenchymal stem cells into osteoblasts.Methods:BMSCs from rat bone marrow were exposed to different concentrations of 17 beta-estradiol(E2) and psoralen proliferation and osteogenic differentiation media.Cell proliferation was observed by Alizarin Red staining,and the secretion of collagen type I and the expression of key factor RUNX2 were evaluated by ELISA and real-time PCR.Results:17 β-estradiol supplements promoted the proliferation of BMSCs compared with the control group.The different doses of 17 β-estradiol(0,0.001,0.01,0.1 nmol/L) added to the proliferation of BMSCs effectively improved the level of type I collagen secreted by bone marrow mesenchymal stem cells,and the mRNA of RUNX2 was also up-regulated.On the 5th after β-estradiol intervention,the expression of type I collagen was significantly increased(P<0.05).On the 7th day of 17β-estradiol intervention,RUNX2 factor mRNA and protein expression increased with the increase of 17 β-estradiol concentration(P<0.05).Conclusion:17 beta-estradiol combined with psoralen can be used as an effective regulator to improve the ability of MSCs in bone marrow regeneration.