Abstract: Objective：To analyze the expression of regulatory T cells (Treg) in peripheral blood of patients with systemic lupus erythematosus (SLE), and explore the role of Treg in cell immunity disorder of SLE. Methods：The percentages of Treg with CD4^＋CD25^＋CD127^low/- in preipheral blood from 50 patients with SLE and 31 healthy controls were determined by flow cytometry. The correlations between CD4^＋CD25^＋CD127^low/- T cells and CD4^＋CD25^＋ or CD4^＋CD25^high T cells, and between the expressions of all kinds of Treg cells and SLE disease activity index (SLEDAI) were analyzed. Results: The percentage of CD4^＋CD25^high T cells in patients with active SLE ［(11.65±5.53)%］ was significantly higher than that of patients with stable SLE ［(8.52±3.15)%］ and of the healthy control ［(6.85±1.63)%］(F=23.287, P＜0.01). The percentage of Treg cells in SLE patients was positively correlated with that of CD4^＋CD25^high T cells (r=0.819, P＜0.05), and of CD4^＋CD25^＋ T cells (r=0.711, P＜0.05). Moreover, there were positive correlations between SLEDAI and CD4^＋CD25^＋CD127^low/-, CD4^＋CD25^＋ and CD4^＋CD25^high T cells repectively for r=0.410, 0.394 and 0.348 (P＜0.05). Conclusion: The percentage of Treg cells in peripheral blood of patients with active SLE was increased, and positively correlated with SLEDAI, indicating that the immunity disorder of SLE may be related to the abnormal expression of Treg cells.