Penile erection is a series of complex and coordinated physiological processes, which is the result of the interactions among multiple factors such as neuroendocrine regulation, hemodynamic changes, and psychological effects. Abnormality in any of them may lead to erectile dysfunction. Nowadays, the number of ED patients is increasing globally and more and more young people are suffering from the disease. A study carried out in Massachusetts focusing on male aging found that among 1290 randomly selected men aged between 40 and 70, the prevalence of ED was 52%, ED has become one of the most concerning diseases that threaten men’s health.