Objective To investigate whether ruxolitinib can slow down the progression of primary myelofibrosis (PMF) by inhibiting angiogenesis at exosome level. Methods Exosomes were extracted from bone marrow samples collected from 3 newly diagnosed PMF patients before treatment (newly diagnosed group) and after 3 month of treatment with ruxolitinib (ruxolitinib group) and 3 primary immune thrombocytopenia patients (control group). The expression of angiogenesis-related factors in exosomes was detected by Western blotting. The exosomes were co-cultured with human umbilical vein endothelial cells (HUVECs) for 24 h. The proliferation ability of HUVECs was detected by cell counting kit 8 method. The cell cycle distribution of HUVECs was detected by flow cytometry. The migration and invasion of HUVECs were detected by scratch assay and Transwell invasion assay. The mRNA and protein expression levels of invasion- and proliferation-related factors in HUVECs were detected by quantitative polymerase chain reaction and Western blotting. Results Compared with the control group, the expression levels of vascular endothelial growth factor (VEGF), VEGF receptor 1 (VEGFR1), hypoxia inducible factor-1α (HIF-1α) and cyclooxygenase-2 (COX-2) in the exosomes were significantly higher in the newly diagnosed group (all P<0.01), while they were significantly lower in the ruxolitinib group than those in the newly diagnosed group (all P<0.01). Compared with the control group, the proliferation, migration and invasion of the HUVECs co-cultured with exosomes were significantly enhanced in the newly diagnosed group (all P<0.05), while they were significantly weakened in the ruxolitinib group than those in the newly diagnosed group (all P<0.05). The proportion of HUVECs co-cultured with exosomes at S phase was higher in the newly diagnosed group than that in the control group, while the proportion of HUVECs co-cultured with exosomes at S phase was lower in the ruxolitinib group than that in the newly diagnosed group. Compared with the control group, the mRNA and protein expression levels of matrix metalloproteinase (MMP)-2, MMP-9, focal adhesion kinase (FAK) and proliferating cell nuclear antigen (PCNA) in the HUVECs co-cultured with exosomes were significantly higher in the newly diagnosed group (all P<0.01), while they were significantly lower in the ruxolitinib group than those in the newly diagnosed group (all P<0.01). Conclusion Bone marrow-derived exosomes can promote the progression of PMF through angiogenesis, and ruxolitinib can inhibit angiogenesis at exosome level to exert the therapeutic effect of PMF in vitro.