Since the worldwide introduction of sildenafil in 1998, 23 million patients with ED have been treated with the drug, and the accumulated experiences have proved its safety and efficacy. This article presents a review about the action mechanism and metabolic process of sildenafil, with a particular focus on the application of sildenafil to ED diagnosis, the curative effect of its daily use on ED, the standard treatment, combined therapy and progressive protocol with sildenafil for ED and its complications, along with such safety aspect as its effect on the sight.