Abstract: Objective To investigate the effect of telmisartan on metabolic syndrome （MS） and its influence on endothelial secretion function in MS patients. Methods One hundred and ninety-eight MS patients were divided into telmisartan treated group （112 cases） and life style-intervented group （86 cases） for four weeks. The levels of blood pressure,fasting plasma glucose,fasting insulin,triglyceride,high-density lipoproteins,nitrogen monoxidum,prostacyclin and endothelin-1 were detected before and after the treatment. Results Comparing to telmisartan group pre-treatment,the levels of nitrogen monoxidum （39.5±10.3） vs （55.5±12.1）μmol/L,prostacyclin （52.6±10.7） vs （74.3±12.8）ng/L were significantly increased （P＜0.01）,and endothelin-1 （54.8±9.9） vs （42.9±8.4）ng/L was decreased （P＜0.01）;Comparing to style-intervented group pre-treatment,the levels of nitrogen monoxidum （40.3±9.5） vs （44.2±8.9）μmol/L,prostacyclin （51.5±9.9） vs （61.1±10.4）ng/L were increased （P＜0.01）,and endothelin-1 （55.6±10.7） vs （50.9±9.2）ng/L was decreased （P＜0.01）. Comparing to life style-intervented group post-intervented,the levels of HOMA-insulin resistance（0.5±0.2）vs（0.7±0.2）and endothelin-1 were decreased （P＜0.01）,nitrogen monoxidum,prostacyclin was increased in telmisartan group （P＜0.01）. Conclusion The insulin resistance,metabolism function and endothelial secretion function of MS patients were improved by telmisartan.