ObjectiveThis study aimed to investigate the stimulating mechanism of p38 mitogen-activated protein kinase(MAPK) signaling pathway and Osterix under intermittent mechanical stretch tension to accelerate the osteogenic differentiation of bone mesenchymal stem cells(BMSCs) in mice.MethodsThree groups of C57BL/6J BMSC, namely, blank control group, strain group, and inhibitor group(p38MAPK signal pathway inhibitor SB203580 + strain), were prepared and exposed to 0.8% intermittent mechanical strain at 0.5 Hz twice a day for 30 min at each time by using a Flexercell strain unit. The cells in the three groups were then harvested on days 1, 3, and 5, respectively. Changes in the mRNA expression ofALP,COLⅠ,andOCNwere detected through real time-polymerase chain reaction(RT-PCR) and the protein expression of P-p38MAPK was observed through Western blot analysis.osterixgene was knocked down by small interfering RNA(siRNA), and Osterix protein expression was determined through Western blot. The mRNA expression levels ofALP,COL I, andOCNwere identified through RT-PCR.ResultsMechanical tension force could promote the mRNA expression ofALP,COL I,OCN, andosterix.osterixsilencing could decrease the mRNA expression ofALP,COL I, andOCN. Western blot revealed that the protein expression levels of Osterix and P-p38MAPK in the strain group were significantly higher than those in the control group(P<0 .05). the mrna expression ofALP,COL I,OCN, andosterixdecreased after SB203580 was used.ConclusionIntermittent mechanical strain promotes the osteogenic differentiation of BMSC via the p38MAPK-Osterix pathways.