Objective To investigate the spatio-temporal expression of nuclear receptor subfamily 0 group B member 1 (NR0B1) in synovial tissues of rheumatoid arthritis (RA), and to uncover the potential upstream signalling pathway that may regulate NR0B1 expression in human fibroblast-like synovial cells, thereby clarifying the possible factors that induce the disorder of NR0B1 expression in RA.    Methods Patients with 25 RA and 18 osteoarthritis (OA) who did not receive any immunotherapy were recruited to obtain the synovial tissues of knee joint, as well as their related clinical test information, and the expression characteristics of NR0B1 in synovial tissue were investigated using Real-time PCR, Western blotting, immunohistochemistry and double immunofluorescent staining. Meanwhile, Pearson Chi square test was used to evaluate the correlation between NR0B1 mRNA expression level and clinical parameters in RA patients. Furthermore, the MH7ANR0B1-/- cells that were stably knocked down of endogenous NR0B1 were generated, and the effects of NR0B1 deficiency on the phenotype of rheumatoid synovial cells enhanced by vascular endothelial growth factor(VEGF) were then evaluated by means of cell viability and apoptosis assays, colony formation assay, wound healing assay, and cell invasion assay. Last, we studied the molecular mechanism underlying interleuikin 6(IL-6)-mediated regulation of NR0B1 expression at the transcriptional level by using the STAT3-specific inhibitor intervention, siRNA, and dual luciferase reporter gene detection.   Results The expression level of NR0B1 mRNA in the RA synovial tissues was significantly higher than that in synovial tissues from OA patients (P<0.05). This trend of the increased NR0B1 mRNA expression correlated to clinical parameters, including C-reactive protein (CRP), rheumatoid factor (RF) and erythrocyte sedimentation rate (ESR), in RA patients. NR0B1 protein was predominantly immunolocalized in fibroblast-like synoviocytes of RA synovial tissues. Functionally, knockdown of NR0B1 expression markedly neutralize the VEGF-mediated enhancement of cell viability, resistance to apoptosis, clonogenicity, as well as migration and invasion in the MH7A cells. Additionally, IL-6 could specifically regulate NR0B1 expression in the MH7A synovial cells. IL-6 upregulated the transcriptional expression of NR0B1 mainly through induction of the phosphorylation of its downstream STAT3 at the Tyr-705 site.  Conclusion The upregulated NR0B1 expression in fibroblast-like synoviocytes is positively correlated with the progression of RA. The proinflammatory cytokine IL-6 potentiates the transactivation of NR0B1 by inducing the phosphorylation of Tyr-705 site of its downstream effector STAT3. NR0B1 may be a significant breakthrough point for understanding the interaction between IL-6 and VEGF signaling pathways and the progression of RA.