As society progresses and health awareness increases, eugenics is becoming more and more popular, and therefore, more and more people are requesting preconception tests. So, what exactly is the preconception checkup for men? The first is the physical examination, which is a specialized examination of the male genitourinary system, including the penis, foreskin, testicles, epididymis and spermatic cord. Generally, through the doctor’s examination, we can understand whether the external genitalia are normally developed, whether there is overcircumcision, small testicles, whether there are varicose veins in the spermatic cord, and whether there is a combination of inflammation of the epididymis. Varicocele is currently recognized as a cause of male infertility, with an incidence of about 15% in the normal population and about 40% in male infertility patients. The incidence of small testicles and cryptorchid is also not low. Some time ago, a young man who was about to get married came to the hospital for examination and found that both testicles were in an infantile state and not developed at all, while his mother was the head nurse of a hospital and had not been found for so many years, which also shows the importance of pre-marital medical examination before pregnancy. The next is the blood test, which includes the examination of the general condition of the body, such as routine blood, liver and kidney function, blood sugar, and thyroid function. It also includes blood type check, because for couples where the female partner is Rh-negative and the male partner is Rh-positive, if the female partner has been pregnant before, the fetus is prone to hemolytic diseases when she gets pregnant again. If the woman’s blood type is O and the man’s blood type is A or B, the fetus is also at risk for immune hemolysis. Blood tests also include screening for STDs and infectious diseases such as syphilis, hepatitis B and C, which can be transmitted to partners and the next generation. With the opening up of sexuality, the incidence of syphilis is on the rise, and many cases are latent infections that can have no obvious symptoms. The positive rate of syphilis is about 2% among women who have prenatal checkups through blood screening. Men who have pets at home, such as dogs and cats, can also be screened for Toxoplasma gondii through blood. Some studies have shown that Toxoplasma gondii can also be present in semen and affect the quality of semen and embryos. If there are more than 2 previous spontaneous miscarriages or embryonic abortions, it is recommended to perform peripheral blood chromosome tests for both men and women to exclude genetic problems. Finally, the semen test is the most important and direct test regarding fertility. Normally, abstinence from sex for 2-7 days is required before semen testing. Too short or too long an abstinence period may lead to inaccurate results. Routine semen testing includes examination of semen volume, pH, liquefaction status, sperm count, viability, and sperm morphology. Decreased sperm count, decreased viability, and increased malformation rates may lead to male infertility. Semen can also be checked for mycoplasma, chlamydia and gonococcal infections in the male reproductive tract, as these infections can lead to infertility or the occurrence of embryonic abortion and miscarriage. If semen is abnormal, it usually needs to be rechecked 1 to 2 times. With the increase in environmental pollution and the stress of social life, the semen quality of modern men has a tendency to decline, and this trend is indirectly illustrated by the downward adjustment of the reference values for sperm count and viability in the fifth edition of the WHO Laboratory Manual for the Examination and Processing of Human Semen. Semen quality may be affected for people who are exposed to long-term radiation, high-temperature work and chemical industrial products, making semen examination particularly important as well. It is the common desire of families and society to have a healthy and excellent baby, and men should take action and take responsibility to do pre-conception tests.