Objective:to explore the mechanism of leeching in treating systemic lupus erythematosus (SLE). Methods: Forty-four patients with SLE were randomly divided into conventional corticosteroid treated group (control group, n =20) and conventional treatment group with leeching intervention added (leeching group, n= 24). Before and after treatment the concentration of plasma endothelin (ET) and soluble interleukin-2 receptor (sIL-2R) were determined. Results: Before treatment the level of plasma ET and sIL-2R in the SLE patients were all higher than those in the normal healthy group, (P＜0.01). But after treatment the level of these in both groups were significantly improved than those of before treatment (P＜0.05), and comparison between these two treated groups showed that the difference between them was significant (P＜0.05).Conclusion: Leeching added to conventional treatment of SLE could be more effective in improving the level of plasma ET and sIL-2R, and ameliorating the impairment of renal tissues.