To investigate the role of regulatory B cells (Breg) in pathogenesis of immune thrombocytopenia(ITP) and its clinical significance.A total of 40 ITP patients and 20 normal controls were enrolled in this study. The content of Breg, Th1, Th2, Th17 and Treg cells were detected by flow cytometry (FCM). The expression level of IL-10,TGF-β, CD40 and CD40L was detected by AimPlex Flow High Throughput Screening Technology.The of Breg cells in ITP patients was significantly lower than that in normal controls (P0.05)，the expression levels of IL-10,TGF-β and CD40L in ITP patients were also significantly lower than those in normal controls (P0.05). The contents of Th1 cells in ITP patients were significantly higher than that in normal controls (P0.05), whereas the contents of Th2, Th17 and Treg cells in ITP patients were significantly lower than those in normal controls (P0.05).The Breg cells may play an important role in the pathogenesis of ITP.