Erectile dysfunction (ED) is a common disorder that affects the quality of life of both men and their partners. The phosphodiesterase type 5 inhibitor is the first-line drug for ED. Recent researches found that long-term administration of low-dose phosphodiesterase type 5 inhibitors to be a safe and effective therapy for ED, as well as for couples who may prefer more convenience and spontaneity in their sexual activities. Besides, it provides a new therapeutic option for refractory ED. Its action mechanism mainly involves the improvement of the endothelial function of penile vessels and/or maintenance of the function and number of smooth muscle cells. However, whether this therapy can maintain the improved erection function after drug withdrawal needs further studies.