Men are at risk of losing their fertility after the age of 70-80 years. A man’s ability to procreate depends on whether he has normally functioning testicles and whether his testicles are good sperm producers, and cannot be generalized. Men between the ages of 70 and 80 lose their sexual function, so they cannot have a normal sex life. In addition, the ability of the testes to produce sperm is greatly weakened and they are unable to produce enough sperm or the quality of the sperm produced is relatively poor, resulting in an inability to function reproductively. Therefore, for male patients usually lose the ability to work for reproduction after the age of 70-80 years, and this time may be earlier for some men due to physical or disease reasons. If they can take care of themselves in general, they may be able to have some fertility before this age. To determine whether a man is in a condition to be fertile or not, he can go for a semen analysis to clarify the vitality of the sperms. The best age for fertility should be around 20 to 40 years old, so it is recommended to pay attention to a light diet, quit smoking and drinking, avoid excessive late nights, and exercise appropriately, which can make the sperm cells grow better, and have some protective effect on a man’s fertility.