Abstract： Objective:To investigate the clinical efficacy of sildenafil in patients with systemic lupus erythematosus complicated with pulmonary hypertension and its effect on serum levels of Type 17 helper T cells (Th17) and thrombospondin-1(TSP-1).Methods:A total of 70 patients with systemic lupus erythematosus complicated with pulmonary hypertension treated in Shuguang Hospital affiliated to Shanghai University of Traditional Chinese Medicine from January 2017 to July 2019 were randomly divided into observation group and control group, with 35 cases in each group by the envelope method. The control group was given conventional treatment, while the observation group was given sildenafil on the basis of the treatment of the control group. The clinical efficacy, systemic lupus erythematosus disease activity index (SLEDAI), and pulmonary artery blood pressure (PASP), and serum Th17 and TSP-1 levels in the two groups before and after treatment were compared.Results:The total effective rate of the observation group (94.29%) was much higher than that of the control group (71.43%), with statistically significant difference ( P<0.05). After treatment, the SLEDAI score and PASP of each group were lower than those before treatment, and the observation group had greater decreases in SLEDAI score and PASP, with statistically significant differences ( P<0.05). After treatment, the Th17 and TSP-1 levels of each group were lower than those before treatment, and the observation group had greater decreases in Th17 and TSP-1 levels, with statistically significant differences ( P<0.05). Conclusion:Sildenafil is effective in the treatment of systemic lupus erythematosus complicated with pulmonary hypertension by reducing the levels of serum Th17 and TSP-1.