Objective:To investigate the effect and potential mechanism of serum exosome-derived cirC_0009362 on the osteogenic differentiation of human bone marrow mesenchymalstem cells (hBMSCs) .Methods:Serum samples from patients with osteoporosis (OP) were collected and exosomes were isolated. The expression level of circ_0009362 in exosomes was detected by qRT-PCR. hBMSCs osteogenesis was induced and the expression of circ_0009362 and miR-29b-3p was detected. The interaction between circ_0009362 and miR-29b-3p was detected by dual luciferase reporter assay. Alkaline phosphatase (ALP) kit was used to detect ALP activity and alizarin red (ARS) staining was used to detect calcium deposition.Results:Compared with healthy control group, the expression of circ_0009362 in serum exosomes of OP patients was increased, and the expression of circ_0009362 was decreased after inducing hBMSCs osteogenesis (all P<0.05) . The ALP activity and the percentage of calcium deposition in hBMSCs were decreased by exosomes, and this effect was achieved by secreting circ_0009362. The effect of exosomes was partially offset by circ_0009362 expression in knockdown exosomes (all P<0.05) . The expression of miR-29b-3p was increased after inducing hBMSCs osteogenesis ( P<0.05) . Circ_0009362 had a targeting relationship with miR-29b-3p, and exosomes inhibited the expression of miR-29b-3p by secreting circ_0009362. The ALP activity and the percentage of calcium deposition in hBMSCs were promoted by overexpression of miR-29b-3p, which was partially offset by exosomes (all P<0.05) . Conclusion:Serum exosomes of OP patients inhibit the osteogenic differentiation of hBMSCs by secreting circ_0009362 to down-regulate the expression of miR-29b-3p.