There are several main categories of male sexual function tests: the first category includes the determination of nocturnal penile erection, nocturnal penile erection is a physiological phenomenon in healthy males from infancy to adulthood, and it is an important method to identify psychological ED and organic ED. The main methods of nocturnal penile erection measurement are as follows, stamp test, hardness scanner measurement, and evening nocturnal penile erection measurement system. The second major category includes penile hemodynamic tests, including penile intracavernous injection test, penile color Doppler ultrasonography, penile hardness test under video stimulation, penile brachial artery blood pressure index, penile cavernography, selective penile arteriography, and so on.