The causes of male infertility are mainly focused on varicocele, reproductive tract infection, cryptorchidism, bad living habits and external pollution, genetics, and sex hormone abnormalities. Men can conduct effective self-examination by some simple fertility knowledge and self-testing methods. If you gently touch along the spermatic cord from top to bottom and find a large worm-like soft and tortuous mass in the scrotum, it may be varicocele. It will raise the temperature of the testicles and the stagnation of venous blood affects testicular metabolism, thus interfering with spermatogenesis and causing a decrease in semen quality. If there is swelling and pain in the testicle, and the testicle gradually shrinks after relief, then it may be testicular torsion or post-inflammatory testicular damage atrophy. This is often accompanied by irreversible damage to the spermatogenic cells. If the testicle fails to descend into the scrotum and remains in the abdominal cavity, it is called cryptorchidism. The high temperature in the abdominal cavity is not conducive to sperm production and the risk of testicular malignancy is greatly increased. Observation of semen can also partially reflect fertility. Normal semen is off-white or slightly yellowish. If it appears pink or red, the semen is hemorrhagic. The normal semen volume is 2-6 ml. If the total semen volume is less than 2 ml, the semen volume is low, and less than 1 ml is considered too low, which is highly likely to lead to infertility. Generally, semen will change to liquid in 15-30 minutes after ejaculation. If it cannot change its form after more than 60 minutes, it is clinically called semen non-liquefaction, which is also a cause of infertility. If a problem is found, a semen analysis can be done at the hospital, which is the most important test to reflect male fertility.