Both microRNAs and T helper (Th) cells involve in autoimmune diseases and their effects and interactions in immune thrombocytopenia (ITP) remain unclear. In the present study, we investigated the expression profiles of seven immune-related microRNAs (miR-155, 146a, 326, 142-3p, 17-5p, 21 and 181a) and the frequencies of four Th cells (Th1, Th2, Th17 and Treg) in peripheral blood mononuclear cell (PBMCs) of ITP patients and healthy controls. Platelet autoantibodies specific for GPIIb/IIIa or GPIb/IX were measured using MAIPA method. The regulating effect of miR-146a on Th differentiation was evaluated after using agomir. Our results showed that the expression of miR-146a, miR-326 or miR-142-3p in ITP patients was lower than that of controls. The frequencies of Treg cells were decreased, whereas the frequencies of Th17 and Th22 cells were increased significantly in ITP patients compared to those in controls. The expression levels of miR-142-3p and miR-146a were negatively correlated with Th17 cells, respectively. The expression of miR-146a was positively correlated with the frequencies of Treg cells and platelet counts. No significant correlation was found between the miRNAs expression and different autoantibody groups. The up-regulated miR-146a expression with agomir contributed to the differentiation of Th17 and Treg in ITP patients. Moreover, miR-146a was increased in the presence of DEX in PBMCs of ITP patients in vitro. Our study represents the abnormal expression profile of immune-related miRNAs in ITP patients, and miR-146a may be involved in Tregs differentiation and function.