Objective To investigate the expression and clinical significance of microRNA (miR-31) in peripheral blood cells of patients with systemic lupus erythmatosus (SLE). Methods Thirty-six patients with SLE and 23 healthy controls were selected, peripheral ACD anti-coagulation blood was obtained, and the expression of miR-31 was detected by RealTime PCR. The relationship between the expression of miR-31 in peripheral blood cells and SLE disease activity index(SLEDAI), parameters of degree of renal injury (Renal-SLEDAI score) and clinical medication was analysed. Results The expression of miR-31 in peripheral blood cells of patients with SLE was significantly lower than that of healthy controls (P<0.001). The expression of miR-31 in peripheral blood cells of patients with SLE was negatively correlated with SLEDAI and Renal-SLEDAI score （r=-0.330，P=0.043；r=-0.337，P=0.044）, while no correlation was found between the expression of miR-31 and clinical medication (P<0.05). Conclusion The expression of miR-31 in peripheral blood cells of patients with SLE may be related to disease activity and degree of renal injury, and may serve as an important biomarker in the early diagnosis, treatment and prognosis assessment of SLE.